To use Uber I think you have to give a credit card. I think this is be biggest deterrent to breaking any laws: they already know who you are and if you commit a crime they can find you. I suppose a gang banger could use a fake credit card to set up an account just to then get a cab and rob them, but that creates a big hurdle that I think will eliminate lots of crime.

That is different then. The parent comment was about money and a smart phone being enough to remove the possibility of picking up a gang banger. Having a credit card on file is a whole different thing.