After 50 Uber rides, I finally ran into an Uber driver who had a sundry shop open in his car. He sold water, gum, mints, head phones, charging cables, bags of chips, red bull, chapsticks, etc. etc.
I asked the driver and he told he can do whatever he wants because he is an independent and the products have nothing to do with Uber, the company. I don't know the legality of opening up a store in the back of a Toyota Camry, but with all legal stuff aside, what are other ways drivers make money? What are cool things they can sell?