Maybe I'm confusing restricted mode with something else? I think it's this: http://i.imgur.com/Kne3CvL.png
I don't think those restrictions are applied automatically. I believe they are set when a video get lots of reports. Maybe it only takes a few reports to restrict the videos, or maybe a human has to evaluate them before flipping the switch. As much as filters suck (I agree with you), I think a few false positives are worth it if we don't show a kid a video of some idiot saying rape is ok.
But I don't use youtube much, so I might be wrong... that's why I ask. :)
In practice, and everyone knows this, filters fucking suck and either have terrible false negatives and don't block awful content, or terrible false positives and block stuff that shouldn't be blocked, or both.
That's nothing to do with this, which is that advertisers don't want their ads next to people saying rape is ok.