> But CCs do charge 1-5% to the seller for the initial ~30 day loan period Are you talking about the balance transfer? I'm looking at this credit card ad from Bank of America and the only time it mentions a 1-5% initial fee is if you apply for their card and then transfer a balance-due from an old credit card to the new one:

Bank of America

Credit Cards: Find & Apply for a Credit Card Online at Bank of America

Explore a variety of credit cards including cash back, lower interest rate, travel rewards, cards to build your credit and more. Find the credit ca...

I also asked an LLM if credit cards charge interest to the seller for the initial loan period, and it says no