If it were, many companies would come in at 0.01% and bank on all the customers that immediately switch payment systems. Or maybe there is a bunch of overhead and investment involved in doing such (personnel, equipment, fraud systems, etc), so no competitor charges a price that would mean break-even or losing money. If a company really doesn't want to use a payment processor, they're free to go back to tab-based/credit-based accounting and hope that everyone pays in cash or everyone pays with ACH.

On that note, I hope FedNOW works well enough to become an alternate PoS payment method[0].

0: https://www.federalreserve.gov/newsevents/pressreleases/othe...