Licenses. Issued automatically, and only revoked for cause. You on food assistance? License is revoked. You involved in a DUI accident? License is revoked.
Buying weed without a license, the seller is fined out the @ss and the buyer goes to jail.
Those who can manage their lives with weed can do so, those who cannot can be filtered out. The majority of people who can do so responsibly will keep the minority who cannot under control by seeing the merits of adhering to the law.
It's what we do with cars, trucks, explosives, plumbing, pharmaceuticals, and other potentially dangerous things.
Licenses. Issued automatically, and only revoked for cause.
That would beat the Hell out of the status quo.