No intervention is going to motivate a dope-sick zombie to get to a hospital as much as the promise of being relieved of it - "can I talk you into coming in for counseling? there's going to be heroin and a nurse with steady hands."
And you entirely cut off the illegal sales market, because the government is never going to provide this service to a non-addict - there's no price at which a dealer survives this market and sells to your kid.
An addict should prefer it to the black market, because they don't have to worry about a fentanyl overdose.
If addicts are being produced out of legal opioids and switching to heroin, then this catches them before they are entirely beyond help.
All in all, this is excellent fiscally as well, because it prevents money flowing out in the dark out of the country (instead, legal imports to doctors) - and possibly, cheaper than ambulances every other week until the inevitable happens.