there are laws against underage drinking and buying alcohol. some kids still get access to alcohol. the law is mostly successful, with an acceptable amount of failure rate.
Gating is not just for porn, they are talking about using for social media and various other things. You can imagine that many things end up age gated if this becomes legislation, as a preventative measure.
Then your 10% becomes problematic because you are either restricting or granting access based on invalid information. So in your world here we then need ways for people who were incorrectly gated to reach out and be corrected somehow.
there are laws against underage drinking and buying alcohol. some kids still get access to alcohol. the law is mostly successful, with an acceptable amount of failure rate.
same concept.