[bhelkey]

> it's illegal for merchants to discriminate against credit cards with high fees

Do you have a source for this? Often times merchants don't accept American Express because it charges higher fees [1].

[1] https://www.bankrate.com/credit-cards/business/why-american-...

[lxgr]

Those rules are about discriminating against various cards from the same brand. They have also been significantly limited in many jurisdictions by now.

[UltraSane]

It isn't illegal but it is against most credit card companies merchant agreements. But I do rarely see it like in some vending machines.