That actually makes sense. You should probably re-think it.
My similar notion is similar to what we call "state stores" in those states where hard liquor can only be sold by the state.
Basically, if you want a drug (besides pot, which should be legal), you go into a state-owned store, where you have to walk past racks of literature offering help to get to a counter where you can buy, for a low price, one or two doses of your favorite toxin. If you buy two, you have to use one on the premises, and you can take one with you. Use the profits to fund drug treatment programs. Have a nurse on the premises. Locate the stores in poor neighborhoods with public transit access.
Couple that with draconian penalties for unlicensed dealing, like ten years for the first offense and life without parole (death in the U.S.) for the second.
Good idea.
Of course a person can be a user and a dealer at the same time. I presume your idea for requiring a person to take a shot on premises is to ensure he's not just a dealer.
But again. If I walk by that shop, unless someone tells me what they sell, I should have no idea. The only information I should see from outside is the street address. Aside from that, I see no shop name, no Open or open hours sign, nada.
If I want to know what that mysterious shop is, I'm free to enter and enquire.
If I own such a shop, I can put up an ad online, advertise my ship's email address as the only contact info in the ad, but I could ore-origram my business email account to send an auto reply with the street address and open hours, perhaps along with health warnings and web addresses for various 12-step groups, and other educational advertising.
In short, it's an out-of-sight&out-of-mind policy. If I'm not looking for it, then I should not see it. If I see it without looking for it, then you committed a criminal offence but with varying penalties. For example, if I just see you carelessly smoking, shooting, drinking, or even just carrying it in public, you pay a fine. Otherwise, if you offer it to me, then hard labour for you.
I would even extend this to tobacco. No more smoking it in public. You smoke it at home or at the shop in a ventilated room that it provides, and all legal shops must be open 24/7/365.
Since alcohol is so entrenched in the culture, maybe allow a restaurant to sell it if it is willing to abide by the strict advertising rules.
Otherwise, a restaurant would reserve the right to tolerate patrons bringing and drinking their own alcohol, maybe even serving it at the table as long as there is no indication if pressure to take it, and people would be allowed to bring their own alcohol to restaurants that tolerate it.
Oh, we shouldn't punish for prescription. Prescription heroin, alcohol, tobacco etc. could be taken in public, but not recreational. Recreational should be highly taxed, prescription not. But prescription, the physician aims to wean you off of it and prescribes accordingly.