...not the point.

I mean, they're at least partly wrong. Only a few states in the US—five, I think?—ban passing on processing fees to the customer. But what's banned is not having different prices, it's charging a fee on top of the listed price.

It's basically a truth in advertising rule, though it's weird that we made it for credit cards and not for sales tax. Anyway, the idea is that credit card surcharges feel like a penalty and cash discounts feel like a reward, even if there's not practical difference between the two at checkout.