i detest signs like these with such a burning passion, they show that people want their streets to be safe but cannot be arsed to actually get them to be made safer, so they put up a sign as if that’s going to do jack shit.
If you want people to drive safely, get the local government to traffic calm the street, if nothing else it’s common for there to be a procedure for getting permission to place some flower boxes on the street to make your own traffic calming.