As long as "drugs" are illegal, they cannot be easily taxed as assets or as items of commerce. Some drug money, maybe a lot, gets to government officials through the back corruption door, of course. Also, many lawyers could be making an honest living on retirement planning, not on springing drug kingpins loose.

So, there is also a potential interest of "government" to decriminalize drugs, but/and instead impose standards of purity and authenticity, as well as tax the incomes of the people who do the trade on a large scale.