The ninth amendment basically means that rights don't need to be mentioned in the Constitution to exist, and that has basis in the Declaration of Independence:

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.

Part of a right to liberty is a right to privacy, and neither are expressly mentioned in the Constitution yet are assumed to exist by the founders. There was even a fight in the early days of the US about whether we needed a Bill of Rights because rights are inherent and don't need to be enumerated.

That brings us to ID laws. If I'm forced to ID myself at every turn, am I truly free? In many states (including my own), I am not required to ID myself to the police unless I'm suspected of commiting a crime (and there's a legal standard there), and even then, I only need to provide my name and address (though the officer made demand my age and explanation of my actions as well). I don't need to provide my ID or any proof.

The only time I need to provide proof of ID (or proof of age) is when:

• buying alcohol, cigarettes, or other age-restricted substances
• I am pulled over for a driving-related infraction (cycling counts), in which case I need to prove I can drive

I am not required to present ID to buy age-restricted content online (e.g. video games). I am not required to present ID to buy things that are legal in another country but not my own (e.g. alcohol is legal in Germany at 16). I am not required to present ID to consume age-restricted substances in my own home, and I am allowed to provide certain age-restricted substances to my children for certain purposes, including religious observance or medical use (up to my discretion, no need to prove anything). I am not aware of any laws restricting that content I can show my children in my own home.

So in general, I do not have to present ID or ask permission for anything I do in my own home. So requiring ID to view a website is an absolute invasion of that privacy that I reasonably expect in my own home. Websites can absolutely choose to verify ID if they want, I just refuse to allow the government to require that. There is all kinds of case law protecting people when they are inside their own home, such as the Castle Doctrine (I can use force to defend my home), the requirement for warrants by police to enter a home (even if a suspect in pursuit enters their own home), and so on.

So no, I reject this type of law under my assumed right to privacy and liberty. I refused to be tracked for doing things that the government doesn't like within my own home.