I think one thing that people overlook is that really, in many labor jobs, smoking is a free break. I remember working in a McD as a teen and quite frankly all someone had to do was ask to go outside to smoke and they got an extra break. That wouldn't happen just for being tired or even needing to pee (i think about the third guy with a newspaper under his arm heading to the men's room ended that one) -- and sometimes even "required" breaks were a joke. But you could always get a yes for a smoke break. In part because most of the managers smoked.