It is a breakdown of parenting. Without taking anything away from the merits of Bible-believing/teaching churches, parents of every faith, or no faith, have a duty to their children and to society to teach some basics of morality. Some basics of self-preservation, for that matter.
Who can know all the laws? It is impossible. But it is very simple to remember a rule that will quickly tell you what the law is likely to be: if you'd hate having it done to you, doing it to others is probably illegal. (And if by chance it's legal, it's still likely to provoke ill will and attempts at getting even, so it's still a really bad idea.) Either way, it's also wrong.
Parents can teach this minimum, faith or no faith.