Businesses don’t need to know they exact percentage to the thousandths decimal. They could easily charge all credit card users x%. If they do not, it is becau

Businesses don’t need to know they exact percentage to the thousandths decimal. They could easily charge all credit card users x%. If they do not, it is because they benefit by people using credit cards because the business is betting they will be able to collect more than x% via people being willing to spend more if they use a credit card rather than other methods of payment. Note that some businesses do not want to place this bet, and have long had lower debit card prices (such as US gas stations). https://link.springer.com/article/10.1023/A:1008196717017 https://link.springer.com/article/10.1023/A:1008196717017