Good. Restaurants are hectic to work in. Menus can change quickly, and many dishes are being cooked and prepped at once. Cross contamination chances are high, so if a restaurant MUST say an allergen is not in X,Y,Z they basically can't have it in their restaurant at all.
They manage here in the UK.
When entering, "any allergens or intolerances" is normally asked before you're sat down. They distinguish the two to decide whether a station clean is required or if they can just point you to the menu.
If it's not already clear on the menu, most medium/large chains then hand you a tablet letting you filter by almost anything.
Alternately, they could truthfully state what allergens are in literally all of their foods, and then people who are allergic to them can safely avoid them, which is what you're expecting them to do now except without actually saying which allergens they are.
In forty years I have very rarely seen menus change substantially.
If you are working with food you should know about allergies. It just comes with the territory. I’m baffled by how this is somehow too hard for US folks yet we manage fine.
Your menus don't change because of the administrative overhead. In the mid-sized American city where I live, menus change seasonally at nice restaurants and daily at really nice restaurants. Even fast food chains experiment with adding new items all the time.
If you're able to change the menu daily, print the menus, walk through the menu with your FOH, then you can have an idea on allergens. Especially in those "really nice" restaurants where the attention is on the provenance of the ingredients (and changing daily because it was what was at the market that day).
It's just yet another arena where the US likes to wring its hands and make excuses for why the US can't do what all manner of other countries manage to do without issue, from things like this to mass transit to Internet connectivity to gun control to ... we're just soooooo unique that solutions that work elsewhere couldn't possibly work here.
The rest of the world has been able to solve that issue