I have spent to many years in avaition security in the inspection role. All to often the equipment in use is purchased as it is the cheapest deal and with many items you purchase in life fails to come up to the spec promised.
In a different role having visted a number of mainland european airports this summer the security performances were nothing short of 'criminally negligent'.
Those staffing them are not well paid and as several have mentioned are not flying on your aircraft anyway. The exercise is performed under pressure with time and social restraints and with the Authorities looking to save monies or cut corners.
Finally the skills of the would be terrorist is such that the likely detection is surely by luck despite all the hype the media spews out. Repeating that already stated the authorities are losing focus on security and it sadly can only lead to some futher act of air piracy.