Whether Uber drivers should be tipped or not is causing frustration for drivers and confusion among passengers, some of whom may be surprised to learn that tipping can impact their passenger ratings.

It's clear from the responses we got to KPCC's query on social media asking whether users tip rideshare drivers that the views range from strong support to reluctance, with many confused about whether tipping is even allowed.

Unlike competing rideshare company Lyft, Uber does not offer customers the option of adding a tip to the fare in its app. It's a sore point for drivers who participated in a nationwide strike last weekend and last year created a petition calling on the company to add a tipping feature.

In its website FAQ, Uber advises: "You don’t need cash when you ride with Uber. Once you arrive at your destination, your fare is automatically charged to your credit card on file — there’s no need to tip."

When users first sign up for Uber they are asked what level of tip they want to include for Uber Taxi — a service unavailable in Los Angeles using the Uber app to hail a traditional taxi. The tip does not apply to the commonly used UberX service.

"That's where a lot of confusion arises," said Harry Campbell, a driver who writes The Rideshare Guy blog. "Tip is not included and it's definitely allowed."

Campbell drives for both Uber and Lyft and finds Uber passengers hardly ever tip. He said he doesn't blame them since the company's messaging seems to discourage tipping.

Those who don't tip, however, may be surprised to learn that they may be penalized with a lower passenger rating score — but more about that later.

Uber's no-tipping approach is intentional, according to author and Duke University professor Dan Ariely, who studies behavioral economics.

"The value proposition of Uber is basically not thinking about money," said Ariely. Because you don't see a meter during the drive, and don't know the total cost until after you're done, Uber eliminates what he calls the "pain of paying," thus making cost less of a factor in using the service.

If customers were asked at the end of a ride to tip, it would be a reminder that the service costs money and might give people a different perception of their experience.

However, Ariely notes that Lyft's tipping system, which prompts users to choose from pre-set tip amounts, can be a very effective way to encourage the giving behavior.

"These options provide social proof of what is acceptable," he said. "The boxes say, 'Hey, most people give 20, 25 or 30 percent.' It makes it mentally easier to give."

Campbell said the debate over tipping has intensified over the last two years as Uber slashed its rates, significantly cutting into drivers' earnings.

Some drivers have taken matters into their own hands, using everything from traditional tip jars to an iPad equipped with the payment system Square to collect electronic tips. But when all else fails, they always have the option to give a poor passenger rating to non-tipping customers.

"Some drivers are probably dinging passengers for not tipping," said Campbell.

You may not know this, but just as Uber passengers are asked to rate their driver, drivers rate their passengers. When a user requests an Uber ride, their rating based on one to five stars displays to potential drivers.

You can ask for your passenger rating through the Uber app. See the instructions below.

Those who achieve a five-star rating can crow about it; those with a lower rating should know they may be marked.

Campbell has his own criteria for how he rates passengers, but he says he tries not to pick up any passenger with a score below 4.6.

If you share your score, we'll share ours. Just use the comments below to brag or whine about your rating.

How to get your Uber passenger rating score

Step 1: Open the Uber app on your smartphone and click on the silhouette at the top left. Step 2: Click on Help.

Step 3: Click on Account.

Step 4: Click on "I'd like to know my rating" and then Submit. You should receive your score within 24 hours via email.

Do you tip? We asked our Facebook listeners, and here's what they had to say.

Do you tip? Comment below