I come from a working class background in St. Louis. Laborers and factory workers absolutely do drink and smoke on and before the job. They don't necessarily show up wasted -- as you say, how could they? -- but they drink. It's less tolerated than in the past, but it still goes on, and it used to be much worse in recent memory, so I have no trouble believing it was even worse before that.

There's a pretty great scene in Season 2 of The Wire where the dock workers are subject to a checkpoint early in the morning on their way to the docks because of a political battle that has nothing to do with them. They've all just come from the bar, of course. One of the guys says to the cop stopping them, "Oh come on! It's 8 AM! Who would be drunk this early!"

I assure you that's meant to be funny.