Those of us who eat certain meats but not others face similar problems. It is frustrating when there is (for example) a meal you're perfectly able to eat, but you pre-booked something else because you can't be sure what you'll get on the day. Such is the reality of commercial operations at scale. I've not tried the 'pre-book a specific meal' option I've seen mentioned on here, which may well improve matters.
There's actually a thought provoking article on this kind of thing by sociologist Susan Leigh Star, called "on being allergic to onions", where she explores how standardisation and commercial imperatives impact on the lives of people with 'unusual' needs - such as an onion allergy. She compares it to, for example, vegetarianism - which decades ago was seen as very eccentric, but now is (more or less) widely catered for - or a Kosher diet.
If you don't fit into a societal norm - through allergy, religion, or whatever - you end up spending a lot of time 'working around' the (often commercial) system that is in place that caters for a majority. In her case, it meant a lot of time asking waiters about onions, and having to repeatedly insist that yes, onion allergy is indeed a thing…