WWW,
Oh dear. You must have your foggles on over this!
Would you rather have ten "PAN" calls instead?
The noise pollution that you suffer occurs because in UK we have D&D; in other states they don't have this facility!
Changing the procedures WON'T stop PPL students keeping themselves out of trouble by calling for assistance (or extricating themselves from it in retrospect if they leave it too late) and it will STILL be on 121.5, whatever the prefix of the call. They are perfectly entitiled to do this and long may they continue to be allowed to do it.
You will STILL get the same problem. Sorry, but your logic is flawed, old chap.