I'm honestly a bit surprised, come to think of it, that all supermarket sales aren't actually accounted as online orders from a webshop hosted on the Isles of M

I'm honestly a bit surprised, come to think of it, that all supermarket sales aren't actually accounted as online orders from a webshop hosted on the Isles of Man with express delivery from warehouse at the customer's location. Then the sale would be on the Isle of Man, and VAT would be correspondingly low. Given majority of food types are already zero rated for VAT what is the benefit to either the supermarket or consumer?