Road safety is increased in countries with more regulations - there is direct evidence across the (developed) world.

Drugs is an entirely different problem that has way more factors that make comparisons between countries rather difficult.

And just because drugs are regulated AND an increasing doesn't mean that the problem is resolved by less regulation. Maybe there is just a need for different / adjusted regulations.

Enforcement is lacking, incentives for criminals are extremely high - cocaine, for example, explodes in value from $2000/kg in the jungle where it's made to $20000/kg after it's been smuggled to the US - and quite a few popular drugs can be made at home using basic tools and skills (cannabis, amphetamine, alcohol, tobacco).

Edit: Clarified it’s about existing legal drugs, not illegal drugs.