In the last week, two different people have captured video of Tesla vehicles traveling down a freeway with an apparently sleeping driver behind the wheel.

Both incidents happened in California. Last week, local television stations in Los Angeles aired footage from viewer Shawn Miladinovich of a Tesla vehicle driving on LA's 405 freeway. The driver "was just fully sleeping, eyes were shut, hands nowhere near the steering wheel," said Miladinovich, who was a passenger in a nearby car, in an interview with NBC Channel 4.

Miladinovich said he saw the vehicle twice, about 30 minutes apart, as both cars traveled along the 405 freeway. The driver appeared to be asleep both times. He wrote down the vehicle's license plate number and called the information in to 911, but the California Highway Patrol had not reacted by the time the vehicles went their separate ways.

Another video of an apparently sleeping Tesla driver was posted to Reddit over the weekend—this one from the San Francisco Bay Area. The Reddit user who posted the video, MiloWee, said that she tried "several times" to wake him up by honking. "It worked, but he fell back asleep," she wrote.

We weren't able to independently validate either of the videos, so it's possible they're pranks. Back in March, a Twitter user posted a video of a Tesla driver apparently asleep at the wheel. Then someone else responded, saying that he was the driver in the video and that he wasn't asleep—he was just "very relaxed."

But real incidents like this have happened in the past. Last month, police in the Netherlands pulled over a Tesla driver who appeared to be asleep and intoxicated. Another video posted in January appeared to show Tesla drivers asleep at the wheel.

In an incident last November, it took police in Silicon Valley seven miles to pull over a Tesla car with an apparently sleeping driver. He was arrested for driving under the influence. Another driver in early 2018 was discovered passed out behind the wheel of his stopped Tesla vehicle on the San Francisco-Oakland Bay Bridge. According to the San Francisco Chronicle, the man "attempted to reassure arresting CHP officers onsite that the car was 'on autopilot.'"

Autopilot may be saving the lives of drunk and drowsy drivers

We should be crystal clear about one point here: the problem of drivers falling asleep isn't limited to Tesla vehicles. To the contrary, government statistics show that drowsy driving leads to hundreds—perhaps even thousands—of deaths every year. Indeed, this kind of thing is so common that it isn't considered national news—which is why most of us seldom hear about these incidents.

Incidents involving Tesla get more attention partly because people are very interested in Tesla stories but also because the design of Autopilot makes it relatively easy for the car to continue down the road without driver supervision.

Some cars don't have lane-keeping features at all, so a driver falling asleep means that the car quickly drifts of the road. Others have limited "lane-keeping assist" products that will warn drivers that they're drifting out of their lane (and possibly jerk the steering wheel) but won't keep the car in its lane for long periods of time. Again, these cars will veer off the road relatively quickly.

On the other hand, the most advanced driver-assistance systems include sophisticated driver-monitoring systems. Cadillac's Super Cruise, for example, uses driver-facing cameras to verify that the driver is awake and paying attention to the road. If it detects that a driver isn't paying attention, it will alert the driver and eventually bring the car to a stop. Subaru recently introduced a similar technology called Driver Focus.

Tesla cars try to determine if the driver is holding the wheel by measuring the torque on the steering wheel. This is better than nothing; if a Tesla driver lets go of the steering wheel, the system will flash warnings and eventually bring the car to a stop.

However, there are ways to defeat this—like attaching a weighted object to the steering wheel. And it's possible for someone to keep their hands on the wheel while they drift off to sleep. Tesla's vehicles also give drivers a relatively long time to put their hands back on the wheel—around 30 seconds in recent versions of the software, though it depends on speed and traffic conditions.

So we shouldn't assign too much blame to Tesla for sleeping-driver problems. Drivers fall asleep in every car model, and Autopilot has probably prevented some crashes that would have occurred without it.

At the same time, there is clearly room for improvement here. Tesla—and other carmakers building driver-assistance systems—could follow the lead of GM and Subaru and add eye-tracking technology to make sure drivers are actually paying attention to the road.