[abalone]

> Square was charging Starbucks 2.75% and Starbucks' average $5 debit transaction was killing them.

That's a somewhat separate issue. That's because Square doesn't charge an absolute component ("+ $0.xx"), not because their percent component markup wasn't huge. In any case, Stripe suffers no such problem.

[CardFellow]

Indeed, and it's part of why Square was a (ha) square peg in a round hole. Incidentally, it's also why they have other pricing now that does have a per-transaction fee.