They know your start location because you call them there. They use GPS to determine your end location, to save time.
Uber doesn't really even publish a rate schedule for how much you pay, and it doesn't have stable prices. They go up during periods of high demand, for example. So it's unclear why you'd object to the GPS, except to mess with them; you don't know what you're going to pay in any case.
So make the destination address optional while booking, and if given you'll get an exact price ahead of time. This doesn't exactly conflict with demand pricing either - Uber just has to be a bit smarter ahead of time.
The fundamental problem is "you don't know what you're going to pay", and I'm not surprised they're being called out for that under consumer protection laws. The point of taxi regulation is to prevent people from being cheated on the spot. Uber is in a position to do even better than what regulations are capable of, with market pricing, and they should aim for that.
Uber doesn't really even publish a rate schedule for how much you pay, and it doesn't have stable prices. They go up during periods of high demand, for example. So it's unclear why you'd object to the GPS, except to mess with them; you don't know what you're going to pay in any case.