How many places in the US test people when hiring them? Up here I've never had it done, nor can I name anyone who has.
Pretty much any major employer is a "drug free" zone, meaning they do at least pre employment testing, if not random testing as well.
I think in most cases it has to do with corporate image (we don't hire pot heads), or insurance requirements.
If you have an accident, even if it is totally the other person's fault, you get tested. That way if you fail they don't pay a dime.
Oddly enough the only employer here in FL that I know for a fact doesn't drug test, is the state. The new governor is trying to make them have drug tests too, along with those on welfare.