It doesn't have to work for everybody, just a critical mass that it doesn't rot the whole country. I can buy enough cigarettes,booze, and weed to run a party 24/7/365, so what are these "limits" you speak of? I don't party like that for the same reasons I quit eating taco kfc mcd's etc. They're still in business, but there will always be a few junkies.

Can people considered underage, ie. children, buy these substances in your jurisdiction? Are there taxation, or limit when and where certain substances or media can he bought or consumed?

If you can sell guns and porn in kindergarten, well yes, you live in a very very ”liberal” society - one that is a dystopian hellhole, that is. Unless there is something very wrong with you, you do not want to live in such a society either. Therefore we have laws, regulations, social norms and taxation to limit unwanted behaviour as well as to protect those in the most precarious position. We all know for instance how mental illness affects likelyhood of addiction, or how such a simple thing as _pain_ made legions of people opioid addicts across the USA.

So no, it is not just few junkies that fail to realise.

In your jurisdiction, are there regulations and taxes on the sale of cigarettes and alcohol?

And are there any comparable regulations on social media?