Well, this is a serious problem and one that requires considerable thought.
However, here is my cunning proposal to solve the issue...free...no charge..gratis.
When approaching immigration, there's a sign that says "Please have your passport and boarding card ready for inspection".
When approaching the gate, there's an announcement saying "please have your passport and boarding card ready for inspection.......".
(Now, I come to my earth shattering suggestion.....)
When that announcement is made why not add"......and keep your boarding card ready for further inspection at the aircraft door for security"..?
Even more cunning, the agent could say " Thank you Mr Strake, have a nice flight and..ooh, please keep hold of your boarding card because they'll need to see it at the aircraft door"
See, brilliant!
The foreigners won't file the card with their passports, the bolshies will have no reason to be..well bolshie. The rest of us can smile, be happy, strum our guitars, hand out peace flowers or generally do what ever we do to try and forget the absolute, total bulls**it ,c**p, pigstink bo****cks beyond belief, that is the commercial flying experience of 2008.