The problem of putting up barriers in the internet has two sides – on the one hand there are governments and other authorities (e.g. religious or commercial entities) that may want to censor unfavourable reports.
On the other hand, there are individuals who may want to block certain web content themselves – either to ensure their children are completely sandboxed from any harm, or to remove adverts and certain unwanted web sites and increase browsing ‘efficiency’. E.g. one could use content rating to only find technical information when searching for some kind of gadget, but no sales offers (which completely spam any search engine’s result).
Naturally, self characterisation of web sites is doomed for failure. No advertisers or merchants would label their sites (or banners) such that they can be sorted out easily.

I think it would be worth a discussion whether these kind of tools would give censorship an easy game, or whether there is a benefit to end users in terms of ‘efficiency’.

One major issue that you indirectly touched on in your last paragraph is that the ratings are effectivly a static point in time, that is You/Somebody decides on such and such a day how it should be rated against the public moral sensability current belived to be prevalent on that day.

Also it is not just “curse” / “Swear” words that change their meaning with time, one extream example being the expression “bachelor gay” which once ment somebody who was activly chasing women (ie lothario / rake / blade). Today most people would give it an almost oposit meaning.

There is also the dual use of a word within a culture which can cause problems as the “The Howard League for Penal Reform” found out.

Also words have different meanings depending on the culture such as Nonce and Decrypt which are common in the security volcabulary. But nonce is used in Britain as slang for a peadophile and in many cultures Decrypt means the same as exhume.

I suspect that any rating system is doomed to fail for these fairly fundemental reasons as well as the more obvious ones.

Other rating systems such as by an official organisation such as the “Board of Film Censors” is obviously not scalable and at the other extream a “web of trust” system (similar to that of PGP Key Rings) where individuals give a page a rating that others might look at is going to have pitfalls in it as has been seen on E-Bay for rating sellers.

From the technical perspective I suspect you are right when you say “so people cast around for other solutions, in my view pointlessly” in that there are none that are going to work.

However from the political perspective people do not want to hear this as they do not want their little “Jimmy” / “Cindy” being subject to such “moraly offensive” materials. So it is easy for Politicians to spend other peoples money on tilting at windmills as long as it improves their raitings. From this perspective (and the kick backs into party funds from greatfull technology companies) these systems are a great success so expect to see many many more of them…

The real solution (though nobody wants to talk about it) is of course the old time tested one of “self responsability”. That is as part of their learning process nearly all children and quite a few adults are going to be curious about many things. And sometimes curiosity leads to them being hurt which is one of the reasons most of us do not put our hands into flames.

Sometimes even quite inocent searches (black holes for instance) will turn up unexpected and possibly quite nasty content this cannot be avoided in a free / open society. Parents need to accept this as one of the ground rules and either educate their children to expect that there will be things out their that will be upsetting and how to deal with it or to compleatly remove access. As history shows the latter option is always doomed to fail.

Oh where you say, “white, middle-class, presbyterian” they have a four letter acroynim for this in the U.S. which is WASP (White Anglo Saxon Protestent) which has alwaysed mildly amused me due to “waspish behaviour” being an almost perfect description of the way they behave

The technical answer to blocking bad things is filtering software run by the consenting on their own (end-user) machines. However, this isn’t cheap — so people cast around for other solutions, in my view pointlessly. So you’re quite right in perceiving that apart from that I have no other answers.