[Gigachad]

A card tx fee of around 1% is common. At 10% it’s tax evasion.

[AnthonyMouse]

If you sell items for $5 and the card charges e.g. 2.9% + $0.30, that's >11%.

On top of that, merchants carry the risk of chargeback fraud or stolen cards, and in some industries that can be another double digit percentage by itself.