Haha I guess we discovered the mysterious country you were referring to when you said, "Elsewhere in the same country." I wonder why you didn't want to reveal it? Could it be because you knew you were wrong, ahead of time?

I'm talking about restaurants, not SEO'd slop recipe sites on google.

> You see both within five minute walks of each other.

Provide an example, then.

Here are some real-world examples:

Red Robin's "Sauteed 'Shroom" burger: https://www.redrobin.com/menu/burgers/sauteed-shroom

Chili's mushroom swiss burger: https://www.chilis.com/menu/big-mouth-burgers/mushroom-swiss... - notice how this one doesn't say anything about a meat patty, except for the picture. That's because without some kind of qualifer, by default "burger" means a sandwich with a beef patty, everywhere in the US.

Buffalo Wild Wings mushroom swiss burger: https://www.buffalowildwings.com/menu/categories/burgers/mus... - also no mention of beef.

Those are chain restaurants which can be found throughout the US, so you can't claim this is something regional. I defy you to find a single counterexample at a restaurant like this. Certainly, this is going to be what you get at any airport restaurant.

Here's an example of how vegeterian mushroom burgers are typically listed, at https://www.barhygge.com/menus : "Mushroom-Barley Veggie Burger". Notice the "veggie". That's what will typically be specified unless you're at a vegan or vegetarian place where it's assumed.