And I'm not even saying that your assessment is wrong, just incomplete. That belief (the politicians thinking that drugs are bad) is largely manufactured, and much of the blame can go to Henry J. Anslinger, yet it has not been sufficiently re-examined by governments in the light of new evidence[0]. Is that out of simple stubbornness or laziness? Or is it perhaps that it still serves the purpose of the state to keep these things illegal? Or is it simply that the state is loathe to give up any power once it has taken it, or even that governments move slowly and we just haven't hit the tipping point yet?

[0] The book to read is "Chasing the Scream: the first and last days of the war on drugs".