If anything, interchange fees should be brought down for credit cards to match those for debit cards. Europe has them capped at rates far lower than the US. With so many people paying with credit cards, retailers have adjusted prices to compensate, which is effectively a consumption tax paid to Visa, Mastercard, and AmEx... even if you don't use a credit card those added fees are still baked into the price. It's only on big ticket items where it's possible to ask for a cash discount, which is usually discounted by whatever interchange fee the store is paying for credit purchases.

Then I found out why the deals were so so good: Discover Card has low acceptance, especially internationally, and this is often because Discover charges relatively high transaction fees. I also learned that Discover, despite its reputation and age, had only one physical branch, in Delaware or something, and so my inner masochist immediately recognized my true financial love.

I also picked up a Discover Bank checking account, which has even lower acceptance rates, but also offers 1% cash-back if I feel like an adventure.

Since then, Discover eliminated their sole physical branch location, and their credit card division was also acquired by Capital One, https://m.xkcd.com/2206/

But I feel like the proliferation now of Apple/Google/Samsung Pay, Zelle, PayPal, Venmo, et al., will stave off any large-scale gouging of consumers through transaction fees.