To duopoly exploiting customers? Europe knocked down transfer fees to 0.2% for debit cards and 0.3% for credit card. All fees for the merchant sum up to something around 1%. So anything on top of that, that Visa customers pay in US is pure exploitation. And US government isn't doing anything so people see alternate solutions for this problem.

The problem of paying 1-3% of every purchase to credit card companies, causing everything to cost 1-3% more.