As far as government intrusion into our privacy, it's addressed by the 4th Amendment's guarantee - that the right of the people to be secure in their persons, houses, papers, and effects and that our rights against unreasonable searches and seizures, shall not be violated.

The challenge is that courts repeatedly and routinely support and protect the government in it's continual, blatant violation of our 4A protections.

This has allowed governments at every level to build out the most pervasive surveillance system in human history - which has just been waiting for a cruelty-centric autocrat to take control of it.

And for the most part, we have both parties + news orgs to thank for this. They've largely been united in supporting all the steps toward this outcome.

As to the first amendment: Although not equal to that of adults, the U.S. Supreme Court has said that "minors are entitled to a significant measure of First Amendment protection." Only in relatively narrow and limited circumstances can the government restrict kids' rights when it comes to protected speech. (Erznoznik v. City of Jacksonville, 422 U.S. 205 (1975).)

> What is the consistent principle of law? I am having difficulty finding one that would support this ruling.

The Constitution of the US mentions age in a few very specific places, namely the minimum age to run for The House, The Senate, The Presidential seat, and I believe voting age.

I don't understand your point.

Some of this depends on whether the state has an interest in preventing known, broad harms - say in the case limiting minors ability to consume alcohol.

Conversely, there are no clearly proven, known targeted harms with respect of youth access to app stores (or even social media). What there are, are poorly represented / interpreted studies and a lot of media that is amplifying confused voices concerning these things.

Which of those are in regard to the 1st Amendment?

> This just looks like another example.

No, it doesn't.

> What is the consistent principle of law?

The 1st Amendment.

> I am having difficulty finding one that would support this ruling.

The judge stated it clearly. And if there's an inconsistency then it's other rulings that violate the 1st Amendment that aren't supported, not this one.

> In U.S. constitutional law, when a law infringes upon a fundamental constitutional right, the court may apply the strict scrutiny standard. Strict scrutiny holds the challenged law as presumptively invalid unless the government can demonstrate that the law or regulation is necessary to achieve a "compelling state interest". The government must also demonstrate that the law is "narrowly tailored" to achieve that compelling purpose, and that it uses the "least restrictive means" to achieve that purpose. Failure to meet this standard will result in striking the law as unconstitutional.

https://en.wikipedia.org/wiki/Strict_scrutiny

Age restrictions narrowly tailored to specific content thought to be harmful to minors have often been tolerated by the courts, but something broad like all book stores, all movie theaters, or all app stores violates all three strict scrutiny tests.

Porn may provide a suitable model: not all movies need age verification, so those can be viewed at any age. Some movies, however, do require age verification. Similar age ratings could be applied to apps. For example, Facebook only after 18 regardless of parent's approval.