I've seen few places accepting only cash or cards from a local payment processor. And it looks like local payment processor takes about 0.16% from each transaction.

So I assume that if they were accepting more expensive cards, they might've increase the price of the $100.16 product for me, to offset their costs.

And yes, I also heard that payment processors have rules that require merchants to have the same price no matter what payment processor (or cash) customer will choose.