Costco used to take exclusively Amex. So it is possible.
In any case, it’s not only the transaction cost but also the availability of an alternative. Forcing a different credit card network is different friction than forcing swipe vs tap. (Or using the Walmart app.)
Do you have any evidence that Walmart negotiated a special deal with Amex to the lower their fees to match Visa and MC?
There are plenty of companies that don’t accept Amex and every Amex user knows that they need to carry a none Amex card with them. Either that or they have never left the country which is doubtful for the Amex demographic.
And I have no idea why this is even an argument on a post about companies wanting you to use their app
Walmart will have a negotiated deal with Amex.
Costco used to take exclusively Amex. So it is possible.
In any case, it’s not only the transaction cost but also the availability of an alternative. Forcing a different credit card network is different friction than forcing swipe vs tap. (Or using the Walmart app.)