Great question.
When Google first came out with a new setting to help filter their search results and make them safer, it had some issues. The main one was that it was a special account setting. You had to manually set it, but if you cleared your browser cookies, it would go away. The interface still looked the same, so you would never be sure if the results would be safe or not. The other problem was that even their "safe" results could be unsafe in some cases.
We saw a need to have a way of ensuring that safe search results provided by Google would always be returned and that they would be filtered enough for schools to use, so we launched KidzSearch.
Schools and homes started using it as their main search tool for kids. We later added many other features that would be safe versions of online products used by adults, like videos, games, kidztalk, wiki, news, and other items. We are now used by over 20,000 schools and millions of kids around the world.
If you ever decide to create something, first find a real need if you want the best chance of getting it to be successful.