They are negotiating with very few entities: just 2 (Visa and MasterCard) account for most card holders. Throw in Amex, and Discover if you want and you've covered nearly 100%.
Merchants don't have a lot of negotiating power, so they are really not in a position to dictate prices. Visa and MasterCard are in a position to dictate prices.
Depends on the territory. In Hong Kong all major credit cards plus several local payment processors plus WeChat and AliPay are accepted at McDonald's, for example.
They regularly do crossovers and promotions to encourage people to use the cheaper ones.
They are negotiating with very few entities: just 2 (Visa and MasterCard) account for most card holders. Throw in Amex, and Discover if you want and you've covered nearly 100%.
Merchants don't have a lot of negotiating power, so they are really not in a position to dictate prices. Visa and MasterCard are in a position to dictate prices.