The most popular taxi cheat is to the take the long way around. Meters don't help you there. Also, meters don't show you the full trip price before you commit.

Uber could perhaps fiddle around with map data, but the history would have to show the correct origin and destination, or it would be noticed. It's trivially easy, and free, to audit against Google maps.

I don't trust Uber to be ethical, but cheating in this space would just be corporate suicide...they would easily be caught.