Wouldn't that be leaving money on the table? The bank that accepts business with marijuana vendors is at a competitive advantage to one that doesn't, no?
There is no liquor store in the country where you can't pay with a card. Well, maybe not Uncle Ted's Moonshine Shack, but realistically it's not something anyone has to worry about. Different funds may not invest invest in those thing, payment processors might charge some businesses a slightly higher premium, but Visa/MC are not gonna police your legal consumer purchases.