Especially because they're trying to "prove a negative", which you can only do by proving everything else positive.
The right solution is to mark everything safe for kids "safe for kids". A simple http header "Age-Rating: 12, MPAA(PG-13), BBCF(12A)" listing the ratings categories they are approved for.
Everything kid-aged and marketed to kids like movies, w3schools, etc will get marked and nobody else has to do anything.
Especially because they're trying to "prove a negative", which you can only do by proving everything else positive.
The right solution is to mark everything safe for kids "safe for kids". A simple http header "Age-Rating: 12, MPAA(PG-13), BBCF(12A)" listing the ratings categories they are approved for.
Everything kid-aged and marketed to kids like movies, w3schools, etc will get marked and nobody else has to do anything.