In reality it’s people with poor or non-existent credit that pay. They can’t access cards that offer rewards, so they end up eating the costs. It’s a remarkably good way of transferring wealth from the poor (who are usually deemed not worthy of credit) to the rich (who are worthy of credit). Pile on the other costs like fees for using cheques rather than direct deposit (also common for poor people who aren’t salaried), crazy overdraft fees etc, and becomes pretty clear that the US banking system is paid for by the poorest in society, and only benefits the richest.

Your reward is basically money paid by the poor routed via the merchant and bank.