[jsonne]

This isn't true in payments. There are many reseller orgs, indie processors, etc. that are happy to negotiate heavily based on volume etc.

Source: I was director of digital marketing for a payments company a few years ago.

[falcolas]

That sounds like the usual "big businesses get extra considerations that small businesses do not". And since small businesses are the vast majority in number, negotiation is absolutely not something they can rely upon.

Or, to put another way, someone selling handmade goods at a fair using Square will never have more negotiation power than "if you don't like it, leave".

[jsonne]

You negotiate by not using square and using an alternative system in that scenario. There are price competitive options even for small businesses. The UI might be clunkier and the equipment more dated but that is the tradeoff.