This, more than anything else, might be the reason that I stop using Uber. I've loved the idea that I can pay a fixed fee, and that I don't have to think about money at all—having to tip, or think about tips, is so much of what I hated about taxis. Uber was great because it was a fixed amount.

If you want the driver to get more money, raise the price. Don't raise the price by making me feel guilty.