Even a ton of Americans wouldn't know In-n-Out. They only really recently started expanding a lot. Until a few years ago its was pretty much a Southern California only thing. There are no locations east of Texas, and even then there are only locations in the core triangle of Texas. If you're in El Paso or Corpus Christi or Amarillo or Lubbock or McAllen or Brownsville you're several hundred miles from the closest location despite there being many locations in Texas. There are zero in New Mexico, Oklahoma, Kansas, or Washington. All of New England is about a thousand miles from a location.

These people acting like "everone knows it" essentially have the same world view that the entire world that matters is Southern California.