Our daughter is allergic to a few things,nuts being one of them.
When we ask for food information at restaurants, often staff have no clue. We had cases where they couldn't confirm for sure even after checking with the kitchen( we walked away).
Servers go by the menu as well. It isn't like there is a list most places.
If the owners cared about your allergies, they'd make sure their staff could find out easily. Blame the folks that own the place, not the servers.
You have the ingredients on a package to check. The head chef can do it while constructing the recipe. And you can explicitly order gluten free substitutes that stay in the freezer until needed.
Getting > 20% of the total revenue in a restaurant seems like a pretty good deal though. I doubt most servers would prefer getting the 2-3x Federal minimum wage and no tips.
And in some states like CA, WA, NYC it’s a (relatively) very well paid job.