I'm skeptical. I've only briefly visited Germany, but my very first experience upon arriving was being scammed by a taxi.
I don't speak German and had been in Germany for only a few hours at that point, so I didn't know for certain that I was being scammed. In fact, I still don't. As far as I gather, taxis are supposed to use their meters to calculate the cost of the trip, but perhaps there are exceptions I am unaware of.
There's a lot of things I find questionable about Uber and its business practices, but the fact that they tell you the price up front is definitely a positive contribution.