[arealaccount]

Only about 15% people tip https://www.businessinsider.com/1-percent-uber-riders-always...

[martinpw]

Important caveat to that study from right at the end of the article:

the data set used for the study, while massive, was limited to 2017 data. [...] Uber only added a tipping function to its app in 2017

So the study was either before you could even tip in the app or soon after and when it was still new.

A more recent study would interesting.