Board-O, I think it's becoming a bit like Lutefisk. As in it's a traditional dish they eat in the US only, because everyone in the home country has better sense than to eat the crap

It's actually fairly regional. It's not something my family ever had or knew about. My Step mom's family is more traditional Mexican, as in they came to the U.S. in the 1930's (vs the 1640's) and they have it all the time on Sunday. My Dad goes golfing to avoid it.
I never see it ordered by 1st generation immigrant Mexicans in any of the local restraunts we go to, it's pretty much a 2nd and 3rd generation thing. Might explain not seeing it in Mexico, or New York City, which I think has a pretty recent Mexican population vs the multi generation we have in California, or Joe sees in Texas.
Birria is a much more popular soup dish around here with new immigrants, although I've seen a few restraunts take it off their menu's because of a severe goat meat shortage we have in these parts.