I think some of this goes beyond acceptance but remember if you shop from them in any way you’re buying from a criminal enterprise. If they’re ignore one law, why would you trust they follow food standards laws? Labour laws? Etc. These are criminal enterprises.
But on topic, I consider it one of the more insidious forms of non-acceptance. Others are things like ‘sorry we don’t allow Google Pay’ and ‘sorry we don’t allow Monzo’. Technically they all take cards, but in reality they’re violating at the least civil law (their merchant agreements), with fees they’re actually criminals, and in all these situations there is de facto non-acceptance. And this is more common than outright no.