Earlier quoted context omitted.
If my kid someone ordered a cellphone without my knowledge and got it shipped to my house and opened it and set it up, I have a lot bigger problems than him finding sex or "wrong" political opinions on that phone. While I know some people at HN would still be mad if the App Store defaulted to "kid safe," it's a fix with much smaller side-effects than outright bans. Assuming "to protect the kids" is really the motive.
Now suppose that clueless suburban soccer mom got her kid an iPhone and doesn't [want to] know anything about configuring this device. Box arrives, she hands it to the kid. Yes, this parent has problems. And it's this situation that Apple thinks they're watching out for.
Oh wait, this already "happens". The phones come with webbrowsers.