But you are right about credit cards, it's not that much.
Right now I'm more or less fored to use paypal. They offer a very similar service. I'm paying a tiny bit less than 10% of my income directly to paypal.
Some small merchants offer cash discounts, but that's comparatively very rare.
Edit: since you mentioned Paypal, I agree that they're horrible to both merchants and consumers. Stay far away if you can. (In fact, I'm curious why you're using Paypal instead of someone friendlier like Stripe.)
That being said, if you play it right you can actually make far more in rewards than the merchants paid. There's a whole subculture devoted to it: I routinely earn around 4-5% back, to the point that I prefer to pay my taxes via credit card even with the surcharge.
Stripe is meant as a suggestion for merchants, not customers.