While I agree with you partially, this is a slippery slope. Sugar and processed food are really bad for you too. Should we start banning or restricting access to those too?
FWIW Mexico does attempt to label sugary snacks with warning labels, more than in the US at least
Compared to meth, crack, oxy, etc they are relatively safe so no we don't need to ban them.
That's the problem. Compared to weed these are highly addictive and cause a lot of harm to the users. Oxy is easily prescribed by doctors whereas there is a taboo against cannabis. It should be the opposite.