And?
I don't get the complaints in the comments from the link you posted: As a customer my understanding is that it does not matter. You buy their product, if they had to charge VAT but didn't it's their problem and liability, not yours.
I am thinking that, realistically, if they have no presence in the EU/relevant country and are not too big then (1) there is little relevant tax authorities can do and (2) they may be considered small fry, anyway.