Actually, after all these years, I just realized that I have no clear idea just what 'zero tolerance' is... um, pardon me, 'ZERO tolerance'.
If your 15 year old daughter comes home and says "Hi dad. I had a glass of wine at the party", do you then ground her? Or throw her out of the house? Or write her out of your will? Beat her? Or shoot her? I guess you must mean something like that....
And then, too, the question arises, why stop at 'ZERO tolerance' ...? Why not go to negative 100? You could, say, like the more ardent and fearless members of the WCTU in days of olde, take an axe and go about smashing the windows of liquor establishments. You could rent a steam roller and and just raze whole city blocks wherein you thought any sort of substance abuse might be occurring. Heck, why not just blow up the whole planet, just to be sure? That would end the problem, I think. And, of course, it would be 'for their own good', right?
In the meantime, do you think it is morally right to use products or services the development of which occurred under the influence of usage of contraband? If not, you'll have to throw out many of the books, movies, and most of the music produced in the last 200 years. Probably, you'll have to lobby congress to pass a bill that says that the 1970's never happened (I think it was Elton John that said "If you can remember the '70's.... you weren't there!") Even Jesus sank a glass of wine from time to time evidently... I'm not sure that your attitude would've been entirely well received at that 'Last Supper' gig. And, as a matter of fact, you'll have to leave the country: The US Constitution was drafted by a bunch of guys the majority of whom drank prodigious amounts of alcohol. (Everyone these days thinks it took them months and months to draft the thing because of erudite debate and deep meditation. Pff~ Half of them didn't get out of bed till well after noon~)
Ah well, like I say, I really have no idea what 'ZERO tolerance' is.