So you cannot compare it apples to oranges. There is much more regulation in EU.

In EU there is also more consumer protection by default, so charge backs can be rejected by merchants but a consumer can easily take a merchant to court. So capping card fees is also more reasonable.

Also, when a merchant goes bankrupt and customers perform charge-backs it would involve the entire payment chain. First merchant reserves, then acquiring bank, then MasterCard/Visa, then issuing bank (customer), and lastly the customer. With lower card fees, this has impact on the merchant reserves and their risk profile. Furthermore, acquirers can add additional fees on top if needed.

You can also get lower card fees in US if you have a low risk business model.