“Credit card issuers explicitly and directly charge the rest of the economy for the work involved in recruiting the most desirable customers.”
Interchange climbs with how upscale the card is, and the merchant pays it. Accounts with 740+ credit scores, roughly 10% of the total, earn issuers the most even after rewards. Starter cards for poorer customers get no rewards and make their money on interest instead. The rich get points and the people carrying balances get the APR.