Right, but how? Wishing it away won't do much.

"Hey! We created this great, convenient new method of paying for things, you should sign up to process all your payments through it"

"Wow, looks fantastic. I'm signed up. One problem, though: you can't tip people through it like you used to be able to."

"Oh, goodness, yes, that's a problem alright. A real bug in the system. Someone should do something about that. Anyway, I've got to go, good luck getting that fixed!"

Well clearly people are happy to pay the extra. We just need to get them used to the idea of doing it in one transaction rather than two.