Aussie asked why Duggar's records went sealed. It's not uncommon in the US for the criminal records of minors to be expunged if the offender is viewed as not dangerous. One of the reason that the police didn't do much in that incident might be that the officer who took the report was later indicted on charges of possession of child pornography (with all of the things that could have been going through his mind at the time of the report). Except for major crimes, records are often sealed at 18.
And it is similar in Australia too, Aussie One just probably has a less criminal past so doesn’t know (;