I was a bit facetious about avocado toast -- that's just a recent trend. Avocado has certainly become a lot more popular worldwide. Avocado toast is but one of the recent avocado recipes whose worldwide popularity has increased.
The joke in Mexican culture is about Mexican culture because avocados are becoming more expensive everywhere in Mexico, not just in some restaurant chain. Mexicans are genuinely starting to becoming unable to afford paying for avocado. The only reason the joke works in Spanish, (e.g. give me some premium gasoline and smear some avocado on it) is because a staple food is getting out of reach.
The joke in Mexican culture is about Mexican culture because avocados are becoming more expensive everywhere in Mexico, not just in some restaurant chain. Mexicans are genuinely starting to becoming unable to afford paying for avocado. The only reason the joke works in Spanish, (e.g. give me some premium gasoline and smear some avocado on it) is because a staple food is getting out of reach.