In the US, Uber doesn't show the presence or amount of an in-app tip until after the driver has rated the passenger, so this is impossible. I can't imagine why

In the US, Uber doesn't show the presence or amount of an in-app tip until after the driver has rated the passenger, so this is impossible. I can't imagine why they'd implement it any other way in other countries. Whatever one's view of tipping, this specific problem isn't likely to be an issue.