I can only assume....
They pay people in the field crap because they do not want people to stay. If they stay, they learn too much. If they learn too much, they might figure out how to get a larger piece of the pie. Or worse, some inside AS might fear that others will learn how to set up a "Not for Profit" international aviation organization to directly compete with them for tax-payer Dollars. For me, it was quite telling when they moved from Redlands California to the Washington D.C. area. The majic of the Lobby Place.
As for their recruitment problem, there are three obvious reasons for it in my opinion. However there is still the security costs question: Is it that AS pays much more to insure security than commercial operators?
Only those in senior managment knows for sure, or, maybe the odd politician.