They're not younger than BoA was either. Or not SM, but I believe GP Basic still holds the record for youngest group (average age of 13.5 at debut) (and the youngest member of GP Basic was actually on her third group, having originally debuted at 10).
I get why it makes people uncomfortable, because of course we want kids to be protected, but generally speaking, it's not the large, publicly well-known, constantly being audited companies that you have to worry about flagrantly ignoring the law.