Depends on location. I'm in the UK, and here if a dish says "mushrooms" without specifying which, it will almost invariably be agaricus bisporus (white/ brown/portobello/crimini/ chestnut/champignon and so on - yes, they are all the same mushroom). As someone who loves mushrooms but Fonda that one utterly boring, it annoys me to no end.

Morels are very costly and I've never seen them offered in common dishes. Usually they are battered and fried and eaten alone, and because they are more rare they do not just freely put them into random dishes.

That's just not true...

If the average dish at that restaurant costs $40 or something, then maybe.