Yes, yes, and yes. However, the three situations you named are targeting adults. Children and teenagers are worth insulating from the full might of advertisers, propagandists, and always-on virtual social circles.
Insurance, defense contractors, pharmaceuticals, home security systems, cars, body spray, McDonalds, Coke, politicians; it's all fear, status, greed. It's explicitly taking advantage of our vulnerabilities with every combination of precision and blunt force, to sell pointless, stupid, toxic shit. Put on your They Live sunglasses. The planet is burning.
Let's advertise carrots on TV. Let's advertise public transport, and public healthcare. Let's advertise free fucking college.
It's been studied under so many different names Knowledge Gap Theory, Info Asymmetry, Bounded Rationality etc The more info Adults have to digest, bad decisions/exploitation are garaunteed.
If you think those legal protections aren’t fit for purpose (they were created long before social media even existed), then you should take that up with your legislators. I personally wouldn’t trust them to approach that task without implementing something horribly tyrannical, like implementing a requirement for a full KYC process for creating social media accounts. So I’d advise that you be careful what you ask for in that respect.
Nothing (besides parents) can prevent people under the age of 13 from joining social media. The kids just lie about their age. Everyone knows how to lie about their age to get something they want, from the time they're in kindergarten.
The value COPPA does provide is as a tool parents can use. If they report their underage children’s social media accounts, they will be removed. But of course they still have to actually do the parenting, which is how it should be. I think you shouldn’t want government to takeover those responsibilities for them.
What makes advertising, I dunno, a remote controlled plane to a kid so much more unethical than advertising it to an adult?
It is possible that this doesn't harm children. However, the deliberate injection of emotional manipulation and disunity into families with young children in order to stimulate the purchase of toys doesn't strike me as particularly good for the nation, and I don't know that I would have to think very hard about my decision if given the option to prevent it using the law.
Do tv shows target teens too much with high energy music and dancing?
Does media target them too closely with intentionally addictive music riffs from Taylor Swift to Billy Eilish?
Will we shut down all these video games that clearly target kids with bright colors and, let's call it what it is, "aestheticized violence"?
We need to be careful about how we go about trying to protect children in this regard.
There isn't really a clear answer to your questions about whether or not "we" would continue to censor video games, popular media, and TV shows if limits were introduced about what minors can see on the internet. It would depend on the compromise reached between the citizenry and the enforcement agency that tasked with enforcing the bans. In some regards, I feel that American life is far too censored and supervised, but in others I feel that it is far too liberated and unrestricted. I happen to believe that there should be more content limitations on entertainment and social media, and less content limitations on political speech. If I were ever to meet with a large group of people who shared my beliefs, we would probably take political action to enforce our will for society.
I suppose that doesn't really prove or disprove your assertion that censorship laws would inevitably lead to more extreme censorship, but I think it's important to recognize that there are already many and forced censorship laws in the US, and altering them isn't really the craziest thing.
If you want to talk about kids cereal the real issue are TV ads pretending to be cartoons. A subject that has generated considerable concern, debate and state action over the years.