When I left Colombia in my late teens in 1970 there was no such thing as an "Estrato", but see that this zoning/caste system was imposed by law in the 90s as a mechanism for residents of designated "higher class" neighborhoods to subsize utilites - electric, gas and water in the lower numbered estratos. So the subsidies are based on where you live, not on your income level. I find it both intriguing and offensive in a way to have such a formalized caste system. I understand that the UN was campaigning for it to be dismantled in Colombia.
How would you characterize the housing in each of the 6 Estratos in Medellin? How would you compare the levels to US housing?
Are there any other expenses which are regulated according to Estrato? Health insurance, health care, Gasoline, food, services?