We don't let manufacturers decide who can buy dangerous things in a lot of cases - so pretty normal to have laws and regulations.
Many dual use technologies, including computing devices, including personal as well as IoT, can be used for a lot of bad things because they are general purpose. And we generally do not limit them at all.
I think that LLMs fall into dual-use category where they are mostly used for good but because they are general purpose can be used for all sorts of things.
If for example you were the Chinese government you may already see LLMs as highly dangerous to your plans of social stability, hence make a lot of rules now on their policing.
That's the idealistic view anyway. A more cynical one might be that in the West, the flow of power from the top down is obfuscated by filtering it through the media and other institutions, who manufacture public consensus, and LLMs are liable to disrupt this system in a way those in power can't predict right now.
And it’s not just filtering incoming spam, spam abusive accounts are regularly removed from service providers.
It's important to recognize where government regulation can help (the unsubscribe links are great!) and where it has limited effect (if you're selling fake boner pills, you don't care about breaking some other law).
Bartenders cutting people off is one well known example. It’s not necessarily a legal requirement, but sellers can have morals just like anyone else.
However if I as a 50 year old, go and buy alcohol from the store, the store has no right to get me to sign a civil contract saying I can't give that win to my 15 year old son, something that's perfectly legal where I live. Nor can they get me to sign a civil contract saying I wont give it to my 3 year old son, something which is not legal in my area.
It doesn't? What prohibits that? Is there a law that requires liquor stores to sell to you if you're 21 years or older?
I'd be curious to know what law or regulation compels a store to sell to you without adding conditions. It might be a bad business practice, but what would actually stop me from requiring customers to sign a document that says a customer won't provide alcohol to an under aged drinker.
Now, I'm not exactly sure what country you are in, but in the US they 100% do have that legal right. Conversely you have the legal right to visit another store that does not enforce that civil contract.
At least for US civil law, you seem to have no clue how it actually works.