I realize this is a broad question, but I’d be interested in personal anecdotes. Are they even common? (Obviously varies by county and region)
They are not usually very good, depending on the city, of course. In Germany, where I live, it’s a struggle to find good Mexican food. It’s never spicy enough and often kind of trashy. There are a few okay, more upscale places with 6-7 euro tacos (yikes) and 13 euro margaritas (yikes). But it’s not as good as in our visits to the US.
Weirdly, when I visit my parents in Helsinki, that city actually has a quite good Mexican restaurant scene. Damn, Helsinki of all places. It’s one of the rare EU cities with Taco Bells (yeah, not Mexican food, I know), and some of the finest Mexican restaurants I’ve visited in Europe. They are quite expensive, but the tacos I’ve had there have been surprisingly good.
In general, Mexico is far from Europe. You can easily find amazing Italian, French, or Georgian food here. In the US, I’ve mostly been disappointed with the selection of French or Italian food. I haven’t found Georgian cuisine in any US cities. So, I tend to enjoy Mexican food when I visit that side of the planet to see family, and mostly focus on European food in the EU.
But damn, I wish there was a diner serving biscuits and gravy in Berlin. Biscuits are one of the things that just don’t exist in Europe.