And, like lots of other things that shouldn't happen, they will. Their parent will be desperately trying to get some work done, or cooking dinner, or watching another child. Children now increasingly get to use tablets for entertainment, and a parent won't be constantly watching the screen, even though it can access the web.
I don't think network-level filters are the best way to address it. But let's stop pretending this is as simple as telling some lazy parents to get their act together.
Why? It's an interactive device that they can play Tetris or Angry Birds on. It's not a stick of dynamite. Most parents will be more worried about what the kid does to the tablet than vice versa. It's only a risky item because some people can't stand the idea of there being any way to access the internet that doesn't include all of the less salubrious bits.
I don't find the Internet tamer now than in the past. Maybe the ratio of non-porn sites to porn sites has increased, but it's trivially easy to find really hardcore porn in video form now with all of the 'tube sites.
I've also heard there have been increased expectations of anal sex from teen girls due to its increased prevalence in porn.
That might have worked when most households had 1 or 2 desktop PCs and a 56k modem between them.
Now, everything is starting to have internet access in one way or another including games consoles.
Whilst very young children might need a lot of supervision regardless, I don't think 12 years olds are going to be too happy with their parents sitting in their bedrooms with them all evening while they play xbox.
What is "unsupervised"?
Children today are given a tablet at the age of three and they tap on it happily.
Do you seriously suggest all people with kids to have a full-time job of watching their kids tap on their tablets over the shoulder?
Who's going pay the wage?
In theory: No they shouldn't you're right. In practice: It doesn't matter. I'm not saying it doesn't have any effect, but me and everyone my age I know grew up with unsupervised internet. 'It never done me any harm.'
I don't think network-level filters are the best way to address it. But let's stop pretending this is as simple as telling some lazy parents to get their act together.