Well the obvious answer is to quit subsidizing negative behaviors. If it's not on my dime, someone can stay drunk 24/7.
But there are a couple of missed subtleties between booze and weed (and yes, they both can be used constructively or destructively). First, there are easy tests for booze -- particularly a breathalyzer. Second, it's hard to capture the initiative-destroying aspect of pot. A person can get a booze buzz on in the evening and wake up ready to take-on the world. Whereas for pot, at least some people <insert pro-pot retort here>, it just fosters more lethargy. While regular booze is bad, regular tweed can trap someone in a demotivational fogthat can last for years.
they have a spit test that can determine the amount of cannabinoids in one's system...would work just like a PBT...and while i agree that pot has some sides, it should be up to the individual to make that call, just like the choice with tobacco, diet, and boozing...the demotivational fog you claim exists, exists treble fold with booze or perscribed medications.
this alleged person who drinks at night and wakes up feeling awesome...well that's a rarity and i think you know that. fighting, dui'ing, fucking skanks, waking up absolutly wrecked and in no condition to be productice...is a much more likely scenairo.
whereas the bro who blazes a joint, will wake up recovered and sober and generally fine.
the physical/mental toll that booze takes is really no comparison to weed.