In short, I have no idea. In elementary school, you learn it has something to do with wearing silly hats, singing funny-sounding songs, eating tacos, and imitating Speedy Gonzales. In fact, the same notion of "culture" is ascribed from all areas of the country: different looking people in different-looking clothes with different-sounding names and different-looking dances. As we get older, we learn these are stereotypes, mainly inaccurate, and sometimes offensive, but its rare we learn what to replace it with. "Culture" becomes another word of "costume", while the real meaning is much more difficult to pinpoint.
Think about it: what's American culture? Baseball? Cowboys? Jazz? Those are all American things, but I don't think they really describe the culture of the country. Maybe it's fast-food, big cities, fast talking, and rudeness. That might be a bit of America as well...but it's not our culture. Do we have a series of songs, costumes, hats, food, and dances that we can wear one day a year and say "it's time to celebrate American culture"? Not really. So why is that the go-to for other countries. It would be like another nation assuming we all wore cowboy hats and jeans all the time while eating hamburgers and driving a hummer. Definitely American sounding...but it has nothing to do with the culture.
So enjoy your tacos, ponchos, maracas, and margaritas today...some people enjoy those to be sure...but be sure you know it has absolutely nothing to do with Mexican or Spanish culture. Only those in the culture could actually describe it to you.