The U.S. consumer economy functions primarily on debt from start to end these days, complete with debt collectors who buy it pennies on the dollar and then con grieving relatives into voluntarily accepting duty towards those debts that would otherwise have been discharged by death. So there are quite a lot of people these days who couldn’t use the European debit methods because they don’t have the cash and likely never will, what with one quarter of the country’s households unable to afford housing on effectively poverty wages. The federal government can’t crack down on this because they’d have to replace that consumer debt with public assistance. The puritanical / religious orgs control majority voting blocs that haven’t aged out as they used to and so are a continued threat to elected officials. So the threat those groups are holding over Visa/MC is triple-pronged: not only will they boycott (they can afford to), they can also leverage politicians (enforce our will or get ejected from office) and threaten capitalism (better economic armageddon than unpalatable sexual expressions). Valve can’t hold a candle to that kind of leverage, not without giving up the neutral-apolitical stance that most tech corporations prefer. They would essentially have to promote a counter-bloc of voters to counter-pressure the U.S. House and Senate into passing payment provider neutrality laws through elections. Valve is vanishingly unlikely to do this, and so their only choice is to prostrate to Visa/MC (or stop accepting USD) until the puritan bloc ages out in two or three decades. They can certainly afford to wait, especially given that these incremental religious bans advance slower than their revenues.