Businesses don't get to negotiate with Visa and Mastercard. They negotiate with banks. And banks negotiate with large volume customers. That's why McDonald's can afford to take credit for a $1 ice cream cone without losing 33% of it to the card company.
Square has a lot of options in the way they process transactions, and they have a very high volume (now more so than ever)
Square has a lot of options in the way they process transactions, and they have a very high volume (now more so than ever)