> MasterCard and Visa have no business unilaterally, secretly, and unaccountably policing their idiosyncratic idea of moral righteousness

That's not why they do it. The reasons are regulatory compliance and risk. Processors would be in big trouble if they facilitate payments when they shouldn't, or broke due to rampant fraud in certain sectors.

I get that you might not like it, but take it up with the US government. The processors would be happy to move as much money as possible to make as much money as possible.