It was regulated away in the Durbin Amendment of the 2010 Dodd-Frank law:
https://www.congress.gov/crs-product/R41913
https://www.ftc.gov/business-guidance/resources/new-rules-el...
American sellers have had the option to collect however much extra they want from people paying with credit cards, and many do. The government, utilities, mobile network providers, insurance, schools, healthcare, gas stations, home contractors, etc all usually collect at least 2% to 3% more if a buyer wants to pay with a credit card.
I am down to only using my credit cards for retail purchases, restaurants, and travel. Otherwise, the extra cost of paying with credit cards don't make sense and I pay with debit card or electronic money transfer (ACH/Zelle).
Basically, the sellers that continue to collect the same price from credit card users and non credit card users are those who believe that incentivizing credit card usage will result in sufficient people paying sufficiently higher prices such that it offsets the processing costs of the credit card transaction (and the chargeback risk).
It is interesting the breadth of experiences in this regard. I pay basically everything on my card, to the tune of 5-6 grand a month, including utilities. The only time I have ever seen a surcharge is for things like contractors doing work at my house. The gas company, electric, the city, all take the card with no extra charge. I rack up a lot of airline miles just from day-to-day use.
None of the utilities for my house take credit card without surcharge.