So could a thermos. So could a ham. So could lots of things. Let's be honest - if you were attempting to hide contraband, you aren't likely to hide it in something that looks like contraband. But you miss the point: the TSA bans things like that sometimes. They ban things like that in some airports. They ban things like that on some days. They ban things like that in certain kinds of weather. Let's be clear - my smaller-than-my-pinky had passed through TSA screening at SEA, SFO, LAS, BUR, LGB, ABQ, PHX, ONT and LAX. The fourth or fifth time through LAX it got confiscated. Theoretically, there should be top-down instruction on what's contraband and what isn't and how to deal with it. There just isn't. Some airports be like "huh cool keychain" and some other airports be like "ZOMG WE COAT THE TERRIST" and those airports might be the same airport on the same day at the same f'n gate. I once had to fly from DC to Dallas to Orange County to Seattle to Las Vegas in two days. I interacted with the TSA everywhere but Dallas. It went like this: - DC: thought I would miss my flight because the lines were so long. Turns out the lines were so long because TSA in DC was unionized and refused to work before 8am. Didn't matter that the airlines had flights that left at 7; TSA didn't give a fuck. No plastic baggie for your shampoo? No problem. They were not the Shampoo Police. - ONT: TSA is all about your shampoo. No baggie? They will give you one and frown at you. - SEA: TSA hands out baggies. If you brought your contraband with you they've got a postal station that takes credit cards where you can mail your pocketknife back to yourself. - LAS: TSA will sell you a baggie for $2. Confiscated items are auctioned off (as they are everywhere) but Vegas is the only place I've ever seen billboards advertising the sale. Having interacted with more than my fair share of TSA employees, I will cheerfully agree that I don't want them using their initiative. However, the TSA is such a poorly-run, poorly-managed establishment that individual initiative is all they have. But things are so much better than they were September 10th back when they were all private contractors, right? riiiiiggggghhhhhhht.
My point was that carrying a foot long bullet/metal container onto a plane should be something that isn't allowed. Even if they couldn't be used as a weapon directly as they were designed, a giant bullet can still do damage outside of the gun. If there is reasonable expectation that the things you mention could be used to smuggle things onto a plane, and that they are too difficult to check, they should be banned as well.
If the AC goes out, and assuming the lines of oxygen masks suddenly stop working? What sort of danger would a big thing of dry ice have in those conditions? People would just put on their O2 masks and the airplane would scrub/release the CO2 from the atmosphere in time. As well, dry ice is CO2, so it would be noticable as everyone gets short of breath, and the big cloud of fog would be a massive tell as well. 3.2 oz of shampoo is an amount not enough for any of the conventionally existing gelled explosive materials to cause significant damage. The limit isn't arbitrary or stupid. http://blog.tsa.gov/2008/02/more-on-liquid-rules-why-we-do-things.html
Can't ban thermoses. They can be used to transport organs and the like and you could totally hide shit between the walls. Can't ban hams. That would gut the tourism industry because people bring food gifts home all the time. You can ban scary things, though. It's always good for some security theater.
They allow Lithium Ion Freaking batteries on the planes but, get this everyone reading this thread, You can carry them into the passenger compartment but not your checked luggage. Don't worry though, they will have new rules for LIon in cargo holds in place by 2018.
Lithium ion batteries are required for phones and other tech to work. Secondly, the "explosions" that these things make aren't anywhere near severe or dangerous enough to damage the plane or be worthy of death. As well, it can take quite some time to get one of the things to explode in a decent fashion so far as I am aware. Cargo holds likely experience a lot of depressurization, heat, cold, and other factors. these would likely damage or cause batteries to have issues and as a result the batteries should probably be kept in a fairly safe, controlled, environment.
The point of the rules is not to outright ban all things which can be dangerous at all, the point of the rules is to protect and ensure that nothing which is of imminent danger to an airplane is allowed onto the plane. People can cause havoc with lithium ion batteries. People can cause havoc with dry ice. The measily little pop and fire isn't going to kill people, and the smoke and warning the device gives off, the tampering required to get the battery to explode are all too difficult to cause substantial harm with. People aren't going to cause the instant death of 5 nearby people with a dry ice or a lithium ion explosion, and setting those things in motion is a very clumsy and hard to pull off sort of thing within the compartment of an aircraft. Again, and I cannot stress this enough, the people running the TSA and making policy decisions are experts at what they do. Despite that their decisions may not seem logical, I am almost certain that if you had the scope and knowledge of the TSA that the people who set these rules do then you would undoubtedly consider the policies relatively tame and reasonable.
And they aren't going to cause the instant death of anybody with a bowling trophy, either. Remember where this discussion started? Me pointing out that the TSA is crowing their safety record and celebrating their vigilance in confiscating a retirement gift from an NFL coach. Not "turned away" not "didn't let on the plane" but confiscated... and posted pictures on their blog... to show how safe they're making the world. Again, and I cannot stress this enough, these are the chucklefucks that spent $160m on pornoscanners. You can be "almost certain" all you want, they are incompetent buffoons that have not, by any applicable measure, accomplished a single fucking thing. http://www.politico.com/magazine/story/2014/01/tsa-screener-confession-102912People aren't going to cause the instant death of 5 nearby people with a dry ice or a lithium ion explosion, and setting those things in motion is a very clumsy and hard to pull off sort of thing within the compartment of an aircraft.