Is it beyond the wit of man (or the pockets of airlines) to develop a link to the transponder so that whenever 121.5 is keyed the transponder squawks accordingly? Shouldn't be too hard, surely?
That'll stop all but ground based and PPL nonsense.
Shy, you don't say "PAN PAN" across the cockpit for the very obvious reason that if you did have your finger on the tit as is all too possible you'd have just broadcast a real one, just as we used to say in the military before setting off practice emergencies, "For Exercise, ......".
A few well publicised prosecutions Europe wide would put an end to it too, I'd think.