I've seen plenty of people drink at work. Most weren't even operating forklifts or anything.  I've even worked at a place where it was standing policy that you could drink after 3 PM on Fridays and drinks over lunch or the occasional workplace picnic?  Oh yeah.  Almost expected in some cases.

One time both my boss and I refused to sign our employer's newly instated substance policy which asserted (among other things) their right to search our cars on company property - not like I could usually find a parking space on company property but neither of us would sign it.

They decided we were both too valuable to push it too far and if we had ever actually gotten wasted at work I'm sure they would have said something - or maybe even fired us.

Bartenders often drink at work too.

And rumor has it that a lot of great writers drank a lot or used other drugs.

Just don't expect to be able to drink on the job if you're an airline pilot - although sometimes they do too.