obviously it is the belief of upper management that low level workers cannot be trusted to behave and work to their maximum if they're on drugs, while the "elites" require such drugs to reach their maximum potential.
Low level workers have the highest chance of getting injured while operating heavy machinery -> highest chance of being drug tested by the police in such cases -> the management would rather spend money on drug testing than on the lawyers later on.
High-paid workers have a pretty small risk of injury -> very small risk of the government testing them -> management is not incentivized to spend money on drug testing (and possible hiring costs later on).
It wasn't that everyone got drunk at work every day, some more often than others, some rarely which made it kind of a special occasion if they stuck around.
He had the same assignments as his coworkers but completed them in half the time. Sometimes, at 11 am, he would just continue drinking beer while sitting in the sun and go home an hour early.
The funniest part was that they mostly talked about work. It was one lengthy extended meeting till 1 am, if they had some kind of deadline they would just work in their spare time while drinking (without pay)
No culture is strange until compared. I drink 2 liters of coffee, smoke a lot and consume lots of sugar. This is perfectly normal here.
edit: it was a desk job
Alcohol at lunch in a business setting was much more widespread at the time.