Mad Jock,
All had something different about them to the standard wannabie eg ex policemen, ex forces (ground types), VSO, TA officers, firemen or self employed running their own business.
The roles you describe don't scream "vive la difference!" to me, but "vive la conformiste!" (excuse bad French, but hopefully you see my point). What I suspect you have identified is that those people who have worked successfully in institutions are probably compatible with the rigid and relatively authoritarian structure of many airlines. Either that or they are simply more closely aligned with the Chief Pilot's background! Personally, it is difficult to argue with the rationality except that anybody who goes in for a mid-life career change porbably has quite a different approach to life, regardless of their background.