Uber originally didn't include tipping, but that changed last June when the ride-share app incorporated the option after drivers were constantly requesting it. While the drivers got their wishes answered, there is now a cap. Uber has set a tip limit—but the catch is that they didn't inform the employees actually benefiting from the new service.

Uber's tipping limit is "200 percent of the total, up to $100," a company spokesman tells CNET. "Of course, riders are free to tip additional amounts in cash if they'd like." So this allows a passenger to tip a maximum $50 on a $25 fare, for example. The change was a surprise to many drivers. "I figured it was just an early-on glitch. It seemed like a bunch of drivers kept emailing us about this," Harry Campbell, a driver for both Uber and Lyft and the owner of the popular Rideshare Guy blog, said. "They never said anything about there being a limit."

Uber explains they set the limit to combat "fat fingers," where a customer could accidentally type in $200 or $2,000 when they really wanted to just tip $20. Campbell also notes the company wants to avoid scams and the 3 percent fee Uber pays credit card companies, but Uber didn't comment on those reports.

But this isn't the only app that has a tipping limit. Lyft has offered a tipping in-app for the past five years and has a similar tip limit policy in place: Customers can either tip up to $50 or 200 percent of the ride’s total cost, depending on which number is lower.