He was caught with nearly 400g of heroin strapped to his body, not in his luggage. He admitted he was transporting drugs. Not a very relavant argument for or against luggage locks.

There isn't a 100% method unless you don't check any luggage. Someone could always pop a lock, cut the shrink wrapping or plastic strap if they really wanted to and place whatever in or take whatever out.

Locking/strapping/wrapping makes your bag a less attractive target, which is how you try to make yourself less a victim. Another thing would be for airlines to keep better track of the weights of checked in bags. Then we'd have a better idea if someone like "Back in 20" Corby was a victim or perp.