I am afraid the only solution is to legalise ALL drugs, use and sale. If we regulate the market we will end up with all marijuana sales in the lovely hands of the CP Group and Central, or possibly Beer Singh and Chang!! Why do we have no CRAFT beer in thailand? Because Beer Chang and Singh don't want them around, even though in reality they are not competition for CRAFT beer at all.
But back to the drugs, 230,000 people in jail for drugs, while they are there, the families are screwed up, no beadwinner. And for what? To fatten the pockets of prosecutors department and the police. If you pay? No jail. So the weakest members of society and up in the clink. The system is so silly as to be unreal. Let's just recognise that there is a market for drugs and stop criminalising it. Alcohol and tobacco are drugs but are tolerated even though alcohol in particular causes far more behavioural issues than marijuana does.