Uphread I was referred to as sheltered, naïve.
Well, I am 50 years old and have an allergy that few people believe. I am moderately allergic to the nightshade family: tomato, pepper and potato.
Think about that for a moment: 50 years old, lived most of my life before any legislation, any awareness campaigns etc. My allergy means I have to watch for:
Bread products - lots a have potato
Vodka, would you believe some of it is spud based?
Breakfast cereals
Sunny Delight orange juice drink
Flavored alcoholic drink mixes such as margarita and daiquiri mix
Some cream cheese, yoghurts, sour cream, cheesecakes, soft ice creams
ALL commercial bakery sweet dough mixes - doughnuts, cakes, coffeecakes, sweetrolls, muffins, quick breads. I once went into the store room and read the labels to a friend who worked in a bakery, very scary how much potato starch is used
Cajun spices
Cayenne pepper
any packaged prepared sauce mixes
Almost every meal in Chinese restaurant foods
mayonnaise - read the fine print, yay! paprika
salad dressings - once you get the mayo idea and read the label it will say paprika or bell peppers or spices, or seasonings. Which I have to assume includes peppers
soups; your mothers home-made, tinned or dried mixes
Hot dogs, pepperoni and sausages - they contain either paprika or cayenne pepper or both)
pimento - easy to miss when stuffed in olives but it is a pepper
pickles - Oh look, cayenne pepper is often included in pickling spice
Most pre-packaged snacks
Anything described as “Italian”
Anything that lists “spices or seasonings” as an ingredient
And don't forget drugs for headaches and many others.
I eat out quite often, my parents used to ignore much of my allergy, it was too difficult to cope with, so I just swelled up every now and then and they avoided things that obviously had tomato in. No one ever believed potato could be a problem. Although prior to the rise in pre-packaged foods I was usually OK. I hate to recall what happened with my first Pot Noodle 
As I got older I had to work it out for myself, no doctor took me seriously in the 80s. As I got older and I reduced ingestion at home, eating out became easier - powdered peppers seem to be the worst offenders.
BUT I still have to read the whole damn menu myself, ask the chef, check when the dish arrives and take full responsibility for my own food health.
Too do anything else is unthinkable. To try to blame a member of staff for poor decisions is pointless, you take full responsibility, anything else is Russian Roulette.
So I eat in small restaurants that make everything from scratch. I explain abut packet mixes and potato starch. Explain that black pepper and sweet potato are absolutely fine and I can usually tolerate some hot seasoning.
So, I do know how hard it is, but I wouldn't set out to move blame onto restaurant staff. If, as OP said It's the first time I have had to deal with it myself. I would have done my research first and made the best choice of restaurant I could.