Size matters. WinCo is big enough to do that, because it's a chain and a brand, and people make a choice to go there despite knowing ahead of time that's how it works. (That said, the first time I went into a WinCo I abandoned a cart-load of groceries because I had neither a debit card nor enough cash with me.) That doesn't work for a small business, like the ice cream shop in the example GP offered. They will be giving up a significant fraction of their custom.

Of course what parent comment said doesn't apply to 100% of businesses, bud I'd say it does apply to at least 80-90%. So I agree with them that it wouldn't work very effectively.