I read a 2015 HuffPost article about this that backs up your idea that a lot of people don’t know whether to tip Uber drivers. According to the author, Uber released a statement saying its drivers make enough money to offset the absence of tips, but I don’t know if that’s true. With all the recent talk about tipping and living wages, it makes sense to tip Uber drivers, but it’s definitely very confusing for users when you can’t add tips on the app. And I personally don’t carry much cash on me, which makes it difficult to tip drivers when I use Uber. I think Annika also made a good point in her comment that it’s the norm to tip in the U.S. but not necessarily in other countries.