Most large trade companies don’t do background checks either, at least not in my experience. Perhaps you missed my statement about not hiring felons? It’s a question on the application. If they lie on the application they get fired. It comes up eventually.
Most legitimate companies don’t tolerate the type of behavior the original poster was concerned about. The employees don’t like liars and thieves. Habitual users of mind altering drugs are a danger to themselves and more importantly to the rest of us. People refuse to work with them.
I’ve been an electrician for 24 years in commercial, residential, retail, and industrial environments. . I’m not speaking from a position of idle speculation nor professional indignation.