Probably because most Brits want the comfort zone of other English people and the amenities on the complexes .
Many also desire the amenities they are used too at home. Fish and chip shops, Curry and Chinese restaurants and English beer 🙄
Most dream of coming to live in Spain because they holiday on the Costa’s…where all the above is available…which is not the real Spain at all.
I can say this because I do live in real Spain. Not a Brit style establishment, fortunately, for miles.