For PICS, once you enable it in the browser (which isn't normally the default) then it does indeed block all websites unless they have content ratings. Which s

For PICS, once you enable it in the browser (which isn't normally the default) then it does indeed block all websites unless they have content ratings. Which seems like reasonable default behaviour, provided that schools / concerned parents / etc are aware that they need to press a button to make the web "safe" for their kids. It doesn't interfere with what adults can do.