I have a friend who classes herself as veggie, but who eats meat from animals which she considers to have a small brain - so chicken, turkey, fish.
I know another woman who classes herself as veggie but who will eat meat products if they don't look like meat - gelatine in puddings and sweets, for instance.
I've been vegetarian for donkey's years and really can't get wound up about what they eat or what they call themselves, to be honest. If they want to delude themselves then why is it any skin off my nose? They're not hurting me, and the only people they are making look foolish are themselves.
I don't think that people like this really give restaurants an excuse to serve fish as a vegetarian option; we're not in the dark ages where vegetarianism was something unusual, and restaurants have to deal with veggies daily. If restaurants don't provide adequate choices then the blame lies wholly with the restaurant, not with the choices of faddy eaters.
My experience is that it's easier than ever to find good vegetarian food choices these days, and I can honestly say that in almost 20 years I have never been offered chicken as a vegetarian option, and only rarely am I asked if I eat fish.