Lot of people do cocaine from all walks of life. It's a lot more common than it was in the 80's, statistically, as far as blue/white collar/ different income levels.
As far as Mexico, it's a different culture. They didn't have the JUST SAY NO REAGAN years, and for many other reasons, have a different relationship with drugs like cocaine, which is esp. in the higher, more sophisticated social classes seen about as common as drinking hard alcohol.
and there's lots of blue collars labor jobs that buy a gram a week after payday. it's just seen as something to enjoy, like a few beers, a cookout, a few lines. lots of people don't sniff lines, they just put a little bit on their fingers and inhale.
white American culture/WASP culture deeply stigmatizes cocaine, and some of that is legit, as in they really practice what they preach --- but just like our puritancial hypocrisy about sex and infidelity, a lot of those guys do-- I have sat at lots of business dinners, million dollar guys, who all do or have done coke.