Waymo has failed to meet the stated goal of CEO John Krafcik, and expectations of the public, to have a fleet of fully driverless vehicles on the roads of metro Phoenix by the end of 2018.

The company is receiving a deluge of media attention today with its launch of a commercial ride-hailing service in Arizona. Participants can hail a vehicle with a phone app, then take the vehicle to somewhere within about a 100-square-mile area, costing about the same as an Uber or Lyft ride.

However, the program is limited and, most importantly, will continue to rely on backup drivers who can take over immediately when the autonomous system has its inevitable hiccups.

"Today, we’re taking the next step in our journey with the introduction of our commercial self-driving service, Waymo One," Krafcik wrote in a blog article today. "We’ll first offer Waymo One to hundreds of early riders who have already been using our technology. Over time, we hope to make Waymo One available to even more members of the public as we add vehicles and drive in more places. Self-driving technology is new to many, so we’re proceeding carefully with the comfort and convenience of our riders in mind. At first, Waymo-trained drivers will supervise our Waymo One vehicles."

This is a different message than the one he was giving earlier this year.

As a March 27, 2018 New York Times article states: "After testing, the company expects to start its ride service by the end of the year. Mr. Krafcik, the Waymo chief, said the company intended to move forward rapidly with a driverless ride service for the public because it was confident its vehicles could operate safely in virtually any driving situation where they would be put into use."

Turns out the company still is not so confident.

The new service, while impressive in its own right, isn't quite the "Johnny Cab" many — including Krafcik, it seems — had thought it would be.

Waymo, owned by Google parent Alphabet, agreed to speak with Phoenix New Times "on background," clarifying that New Times could not directly quote representatives.

Waymo's autonomous vehicle depot in Chandler. Ray Stern

Waymo acknowledged that while the company will continue to test fully driverless vehicles in limited fashion in metro Phoenix, it would not have a fully driverless ride-hailing system for a long time to come.

Waymo said it still has much to learn about deploying such a system, but downplayed safety concerns, indicating that the cars are making remarkable progress. While safety is clearly the highest priority, according to the company, one key reason for the lack of a fully driverless service now is comfort and convenience.

Early riders who become part of the initial ride-hailing service launched today are not only used to the quirks of the vehicles, but will ride on routes that are the most well-mapped by Waymo. That'll further increase riders' perception of comfort — the vehicles have more experience on those routes, and will react more predictably to things they encounter.

New Times experienced one such quirk in a ride in a Waymo vehicle (with a backup driver) in late 2016, when the car refused to pass a slow-moving street-sweeper in its way.

While the technology has improved since then, Waymo said a car may still occasionally take too long, from the riders' perspective, to merge into traffic when other drivers are being assertive. Its cars also may slow down momentarily for invalid reasons, like uncertainty about whether an object or person on a sidewalk needs to be avoided.

On other occasions, the cars may do something legit, but early riders felt confused or frustrated because they didn't understand why a car was doing it, Waymo said.

Without doubt, safety remains a concern for these experimental vehicles on Phoenix roadways, especially since the March 2018 death of Elaine Herzberg.

Herzberg was walking across a street with her bicycle when a self-driving Uber vehicle plowed into her without braking. Its automated collision avoidance system had been disconnected for a smoother ride, and Uber's backup driver, Rafaela Vasquez, wasn't looking at the road while streaming a TV show on her cellphone.

Yavapai County Attorney Sheila Polk has not yet announced if she'll charge Vasquez with a crime. Polk's office is investigating because Maricopa County Prosecutor Bill Montgomery said he had a conflict.

Waymo submits reports to California each year showing how often its backup drivers took over for the autonomous vehicles, but doesn't submit them to Arizona, which requires almost no regulation of the experiments on public roads.

The reports don't differentiate by test city, but show that in 2017, Waymo vehicles required human intervention once every 5,600 miles. Not all of those interventions meant the car was being unsafe or would have crashed, the company claims. But even without better data from the company, it's a no-brainer that when the automated system fails in some way, a fatal crash could result if no backup driver is in the driver's seat.

As Krafcik indicates in his article today, the new service will not be for the "public," as yet. Media representatives still have not been given a demonstration ride in a fully driverless vehicle around metro Phoenix. Governor Doug Ducey, the state's biggest champion of autonomous vehicles, sure as hell isn't stepping into a fully driverless one, despite an offer from Waymo to do so.

Even overlooking problematic glitches that could bring an autonomous ride to a crumpled end, many experts say the "edge" cases, which are situations that the car isn't programmed to handle, will keep fully driverless vehicles from becoming common anytime soon.

The world's a complicated place, and computers are not as good as humans at detecting clues from the environment to predict what will happen next in completely new situations.

Today, we're taking the next step in our journey with the introduction of our commercial self-driving service, Waymo One. #everystep https://t.co/Sg2a5wRVfM pic.twitter.com/kRZtA4gRda — Waymo (@Waymo) December 5, 2018

Waymo told New Times that visual clues humans would have no problems reacting to can be difficult for its cars to detect. Hand signals or the look in a driver's eyes are things the vehicle's Lidar and radar systems just can't see.

Another problem is that the automated vehicle may have a destination address, but may not stop to drop the rider off at a convenient spot for the address. Waymo acknowledged that mapping private property, like the parking lot of a large event facility, was an ongoing challenge.

Even when a fully driverless system goes online at some point, humans will be needed at a remote control center to help keep things running smoothly, the company said.

For instance, if a Waymo vehicle comes upon a stalled car in the middle of the road, it may hail the control center, whose human operators could see the problem on video and take corrective action. Or, if it's pulling up to an intersection and all the streetlights are out, it might call the center and ask whether it should treat the intersection as a four-way stop, or take other action as needed, Waymo said.

Notwithstanding the current limitations of Waymo One, the new ride-hailing service itself will result in more information for the public about the operations of Waymo vehicles. While the program will be limited for now to the 400-or so people who participated in the Early Rider program, those people will no longer be restrained by a nondisclosure agreement. They'll be able to write or speak about their experiences, good or bad. And they can take guests, perhaps including the news media.

But Waymo One vehicles won't be fully driverless, except on rare occasions. On a recent visit to the company's Chandler depot, eight self-driving vehicles pulled up over about 30 minutes, and all had backup drivers.

Whether it takes years or decades to acquire the necessary technology, a fully driverless taxi service seems to be inevitable. But it's not here yet.

(Correction: Waymo got back to New Times after this article was published to say that after clarifying with engineers, their vehicles do detect turn signals on other vehicles.)