"These “Trusted Passengers” are given just a cursory check. Some of them may accidentally bring a firearm onboard like this man did."
Someone who doesn't know where his gun is, at all times. Yeah, I trust him. The moron.
That said, El Al is on the right track.
If you want good security, you select, you train, you pay decently. You have a multi-layered system. You check out the pax in various ways, you check-out airport employees, you secure the airport and you ensure the aircraft are security checked regularly.
Complacency will always be the enemy and the downfall and is usually all too evident.