"Because most of the data in the US indicates no correlation between enforcement and addiction rates."
This is simply not true.
This notion that legalizing something will incur less addiction is simply not reasonable.
Opiates are available by prescription and that is huge source of addiction, even within that controlled environment. Doctors in Canada now give out the absolute minimum - I had major dental surgery and got two pills. Just two! Because it's that addictive. US doctors are changing as well.
Consider what full opiate legality would mean: it would be infused into tobacco, cola, alcohol, food etc. and available within an arms reach with billions in advertising behind it.
Even though a good number of people wouldn't use it, and another chunk can actually 'handle their drugs' - for a significantly high group of others it would be destructive. If only 5% of our population fell prey to this, and instead of having jobs they were stealing, in hospitals, rehab etc. - it would be a huge crisis.
I'm always surprised by how people put this issue mostly in the context of the here and now, and don't consider how so many things would transform.
Vaping (i.e. repackaging of nicotine) is blowing up massively in the US, Juul is hiring 2000 people just in SF and their business is exploding! This is not because vaping 'tastes good'. It's because it's deeply addictive, and as an ex-vaper (short period) I suggest there's a whole host of problems we haven't seen yet.
No good will come of a generation re-addicted to nicotine.
So yes, Portugual et. al. took a different path on hard drugs, but this is nothing remotely near legalization. It's still a health problem, they just deal with it differently.
Mushrooms are a different thing, they are not remotely addictive, so they're in a different class. That said, they are actually dangerous. Also the inherent demand is just not nearly there. Some degree of de-criminalization ought to be considered surely.