As far as I'm aware, Uber drivers don't see whether you tipped or not until after they have rated you.

I suspect it is true since I never tip on Uber and I have a 4.96 out of 5 star rating.

They initially billed themselves as no tipping necessary. I refuse to subsidize driver wages on behalf of Uber. There is no way Uber is not benefitting from tipping by being able to keep wages lower as a result.