Polite notices

In the past I have always thought that the 'No Ball Games' sign was the most annoying occurrence in modern life (heaven forefend that kids be able to kick a football around on your precious patch of grass) . Its rival for me at the moment is the 'polite notice' - e.g. 'polite notice please have your change ready when you get on the bus', or 'polite notice please do not smoke in this area.' Who are the writers of the sign to say if the sign is polite or not? This is surely something that we should be the judge of – just say what you want to say and let us place it within our own schemes of courtesy thank you very much.

Perhaps it is now acceptable to write or say anything so long as it is prefixed with the words 'polite notice'. e.g. 'Polite notice all our customers are the dregs of society', or 'polite notice none of your sort here', and so on and so forth.