A few years ago I developed a potentially life-threatening allergy to something and after ending up in A and E, was fast-tracked through the NHS allergy clinic at the local teaching hospital. No waiting list for me, fantastic and very prompt treatment with a top guy, great care generally.
The waiting room was absolutely rammed with women banging on about wheat and dairy allergies and problems with this food and that food, who had been waiting ages for appointments. I was quite shocked because a) What has this to do with the rest of us? Why announce this publicly? and b) I assumed some dreadful thing had happened like peanuts where there was a massive increase in dramatic allergies generally (hence what had suddenly happened to me, which was not food-related, by the way).
I mentioned this to the consultant and he smiled and said the number of actual cases of anaphylaxis they came across were really comparatively small, which was why I had been fast-tracked, and most of the women in the waiting room were likely to have nothing wrong with them. Peanut allergies were apparently more serious and on the rise so they had developed treatments for that. I inferred from this that intolerances and pseudo-allergies have become fashionable conditions and people fuss about food too much. Believe me, from my experience, if you have one you would really know about it as it is so frightening (you would get seriously massive hives and swellings and/or stop being able to breathe properly, etc). Hollywood films do not do life-threatening allergies justice IMVHO.
I think this then translates across to quasi-veganism and quasi-vegetarianism, and people thinking it is OK to fuss publicly about not eating this food, and that food, and the other food, and everyone has to accommodate it because they say so and they are special. So it's gone well beyond, say, not eating animal products as a religious or lifestyle decision or biological necessity. You end up seeing people announcing this, and expecting special treatment, then when they fancy a bit of something that breaks their food code, they do what they want when it suits them. In other words, for an increasing number of people, none of this is about the food itself, it is in fact a kind of power play.
You can tell the real vegans and vegetarians, etc, or people with a serious allergy or concern, because they don't want a fuss made and they organise themselves behind the scenes to ensure a problem doesn't arise. They don't catastrophise things like soya milk not being there, because they have a few of the portion packs ready in their hand luggage. Just like I always have my allergy medicine in my purse at all times. Other people who routinely have to do formal dinners and visits away from home that cannot be avoided, and have horrific allergies or major intolerances, usually have a pre-prepared side of A4 that lists the things they can eat that can be easily supplied, and they send this out whenever they are making an eating arrangement. In other words, they are focused on the 'can' and not the 'can't'.
So OP, next time, either pack what you need or be a better guest and give proper advance warning of your particular requirements.