When I make, say, meat loaf, at home, I know that I use ground beef, Panko, egg, onion, ketchup, vinegar, oregano, and garlic. If somebody asks whether there's ground beef, wheat, onion, tomato, vinegar, oregano, or garlic in the food, I believe a waiter could give a correct answer. But if somebody asks about yeast, or high fructose corn syrup, the waiter might have to ask the cook, and the cook might need to look at the label for the Panko or ketchup (surprise! packaging for restaurants may not have the same information as consumer packaging).

If somebody orders, say, ribs, and mentions they are allergic to spices that are found in some barbecue sauces or spice rubs, the waiter isn't going to know (and the cook might not know) if those spices are in the dish, and especially won't know if they're present in a large enough amount to cause a reaction.

The FDA does require manufacturers to keep track of the most common allergens ( https://www.fda.gov/food/nutrition-food-labeling-and-critica... ), but if somebody has an uncommon allergy, they're on their own. Restaurants are regulated by state health departments instead of the USDA. California, I believe, has some allergen labeling requirements for its restaurants. Most large restaurants worry enough about liability that they disclose the information (for common allergens) voluntarily.

In general, I think the barrier to entry to providing goods and services is now high enough that it discourages ever larger numbers of businesses from ever being started in the first place.

The labeling and disclosure is pretty much solved. The killer and the cost monster is the handling. That's why you see that "Processed in a facility that also processes XYZ" label on some foods.

I had an old coworker with a severe milk protein allergy. So bad that he would get a reaction if he (lip) kissed his wife after she drank milk or had ice cream. So eating out was basically impossible, because his food would pretty much need to be made in a totally separate kitchen to avoid any contamination risk.

So we are right back at my point. Do we force every restaurant to have a secondary allergen free kitchen so my coworker can eat there? Or does my coworker just deal with it and stick to vegan places (like he did)?

If your point is that cost doesn't perfectly match frequency, sure, it was off the cuff, but it doesn't change the underlying nature of "accommodating everyone".