It is a stupid law but I feel people are overthinking this.
For compliance the os has to provide an age category to an application and an interface for the user to enter this data. We already have an api to provide information to applications. it's called the filesystem. and an interface to enter the data, that's called the shell. so everything is already there. If the user lives in california and wants to be compliant (wait a minute, let me stop laughing) all they have to do is put a file somewhere with a age category in it. if the application can't find it. well it's not their fault the law is stupid.
I'm not a lawyer. But it seems to be the same as accepting the terms of service of some product you use or clicking on a "Yes I'm 18+" button to gain access, isn't it? If you somehow suffer from a negative outcome, it puts the blame clearly on you, from a legal standpoint, if you lied about your age or ignored the TOS.
It says nobody is liable for the signal being wrong i.e. the parent is allowed to give the child an over 18 account or full access if they think that's appropriate.
Without that file, I hope the age category generalizes to 0. Also, I suppose the file’s ctime should be subtracted from localtime and added to the age, but maybe not if the special value 0 was entered.
For compliance the os has to provide an age category to an application and an interface for the user to enter this data. We already have an api to provide information to applications. it's called the filesystem. and an interface to enter the data, that's called the shell. so everything is already there. If the user lives in california and wants to be compliant (wait a minute, let me stop laughing) all they have to do is put a file somewhere with a age category in it. if the application can't find it. well it's not their fault the law is stupid.