>There is perhaps nothing more quintessentially American than the fish stick.
uh....
uh....
The only thing I can come up with about which you could credibly say that "there is perhaps nothing more quintessentially American", is American Football. Literally the entire rest of the world plays regular football instead. There are American Football leagues outside the US (or there is at least one), but my impression is that they rely very strongly on American athletes who couldn't quite make the NFL.
Everything else that feels quintessentially American (apple pie, fast food, ketchup, fish sticks) is less quintessentially American than that.
The others? Well, maybe. Most of them are not strictly limited to the US, but the US does tend to put a very unique spin on them. For-profit healthcare exists elsewhere, but medical bankruptcy might well be strictly limited to the US.
I'm willing to settle for medical bankruptcy being the most quintessentially American thing.
> Greeters in stores?
Quintessentially walmart. Can't say I've seen any other store do that.
For the purpose of Cowboy/Rodeo culture, Mexico and the US are (figuratively) the same country. That is, there was a cowboying cultural region and a border got put down the middle of it very gradually. Texans were cowboys before they were american, californians, etc.
My grandma made apple pie and she was Romanian and had never been more than 200 km from her village. She definitely didn't learn the recipe from US TV shows :-p
From other countries it still sounds like a weird saying. Dutch people love apple pie every bit as much as Americans do. Apple pie is something quintessentially loved by people all over the world. From my (Dutch) perspective, cheesecake is far more specifically American than apple pie. I love cheesecake, but it's not as rooted in my tradition as apple pie, and feels more like an American import.