I actually found out a few days ago that in some countries Uber does accept cash (like Singapore - https://www.uber.com/cities/singapore/ https://www.uber.com/c

I actually found out a few days ago that in some countries Uber does accept cash (like Singapore - https://www.uber.com/cities/singapore/ https://www.uber.com/cities/singapore/). But it's still not anonymous, obviously, because your user profile is still tied to the ride.