When I get on one of my hobby horses I have so much fun!
The guy in the story typifies what is going on. First he was not a terrorist. Second the airport security failed to stop him from carrying on two banned "weapons" (they did not find them despite having probably one of the best security systems in the world. They only found the knife when he told them about it!). Third, as in most circumstances, the problem will not show up at the airport but in the air, a situation ignored by authorities. And Fourth, real terrorists will not try to smuggle a knife or gun, they will use weapons that are not detectable or are not banned. I do not want to tell you what works, but you can look at the stories of the last twenty or so hijackings, some of which were successful. Only one guy used a knife, a small pocket knife and he was unsuccessful, did no damage. In one of the successful hijackings, the perpetrator used a TV remote control. Airport security cannot and will not be able to prevent a determined criminal or terrorist, and the effort MUST change to one of detecting those people before they strike and to develop ways to handle the attack in flight. Both of these necessary areas are being ignored in preference to treating the passenger as the enemy. All the effort is being put into making the honest person's life miserable; they have no resources left to actually find the bad guys. When they waste their time seaching a little girl's bag you know they have no clue.
I don't know about Aus, but in the US they have put in great big special Xray machines to detect explosives in all passenger bags. Now where do you suppose these machines are located? Down below or out in a remote area so that if they find a bomb they can dispose of it safely? No... they are generally right there in the check in area, so that if they find a bomb and set it off, maximum casualties will result. And when the machine does trigger a response to a potential bomb, do they call the bomb squad, dogs and the lot, and move the suitcase to a safe area before opening it? No, they put it on a table right there beside the machine and go through it manually, using rubber gloves! A bomb would most likely have anti-handling devices, so rummaging around in the bag is sure to set it off, so what do these brilliant security experts do? It tells me that they know there is no threat, and they are doing it for their own agenda, not safety.
And consider the security lines. What happens if they did find a terrorist with a gun? Do they think the terrorist is just going to hand it over and go quietly? Of course not, he is going to pull it out and start firing! What response can the airport security make to that, with thousands of innocents standing around? How can they take the guy(s) out without causing more casualties? Man, look at the way they respond to finding a computer in a carry-on, imagine what would happen if they actually found a gun and a real bad guy together? They could make a movie and use it to show how it should not be done.
My point is that they know there is no threat, and they are not prepared to deal with it if it did exist. They are just going through the motions in order to reassure the gullible public that they are doing something to make flying safer, even though in fact what they are doing makes us all less safe. But it does let them build a bigger empire!