I think his point is that wealthy people spend more, so the card brands can charge more interest to the merchants. If you spend $20,000 and Amex charges 5% t

I think his point is that wealthy people spend more, so the card brands can charge more interest to the merchants. If you spend $20,000 and Amex charges 5% that's $1000 in fees. But a poor person who spent $500 only earns them $25 in fees to the merchant. Now it's true that the poor person if they can't pay might pay 20% interest, but the real money maker for the card brands is not the late payment fees but the processing fees which is the gist of the lawsuit and the article.