It was a surprise to me to learn that Colombia has a class system. They call them strata, with strata six at the top. Apparently, the strata system determines the cost of utilities etc. and has nothing to do with class.
Expats are considered strata six. This makes me think that there is a strata seven — as I’ve seen many “strata seven” types out and about in my neighborhood. 
May 1 is not such a big deal here in Colombia. Neither as international workers’ day nor as a spring festival.
The estratos are based on your address. One newer building in a nice neighborhood might be estrato 6 while one across the street is 5 or 4. The higher your estrato, the more you pay for water, gas, and electricity. This essentially means the wealthy subsidize the utilities of the poor. It has nothing to do with whether you’re an expat or not, though often the terms are used loosely to describe people.
Thanks for your comment. I guess my point was that some expats like me live in the higher strata numbered areas.