Bulletproof clothing only protects you against bullets (well it protects against knives too but you can buy less expensive slash/stab resistant clothing). In Australia there is virtually no gun violence. The only people who can shoot you are cops. They will only shoot you if you're doing something that justifies being shot at. Therefore, the only reason you'd need bulletproof armor is if you intend to do something that would justify the police shooting at you.
Encryption on the other hand has legitimate purposes. It's quite possible for someone to say steal all your money by intercepting your bank account login and it requires no special, heavily restricted equipment to do so.
Also, it’s trivial to make effective rifle armor out of AR500 steel, Rhino Liner (or other bed liner) as a spall guard and a nylon/Velcro plate carrier which will not tax a third year cosplayer in the least to sew.
And ISIS, as has been shown in France.
In reality, law and society are complex creatures. I'd observe that any knowledgeable person observes encryption is commonly and widely used for a variety of purposes, and has many people who will push back against its denial of use.
In terms of the body armour law, there would presumably be the empirical facts that:
1.) There's just not actually a demand for it amongst the society in the aussie context at least.
2.) The odds of being shot or stabbed by someone other than a close relative is virtually nil in Australia if you're not partaking in a criminal enterprise. And so far as long as those criminal enterprises don't spill over into public related injuries and violence, people's level of fear regarding guns/stabbings is pretty low.
3.) This must be taken in the context of an everyday culture that has a rate of ~1 in 100,000 rate of homicide (non-uniformly distributed admitedly) compared to the united states rate of ~4 or 5. The culture is relatively uniform, and united states-esque laws and policies regarding weapons and obsessions with are generally viewed as a mixture of "crazy", "a warning of what we could become", and just a generally undesirable state of affairs.
There is a debate regarding encryption. Whereas debate around things like increased access to weapons or body armour is "effectively zero" in the context of Australian society (keeping in mind I don't have the time/space to go into the historic details or rural hunter/fisher/farmer politics).
I'm going to assume that canadians in many ways view american laws/society in a similar vein to us in this context: our friendly but crazy relatives. (albeit with them sharing a physical border).
I'm also guessing (I haven't looked it up) that they have a far lower homicide rate, and would suggest, like Australians, that they believe de-escalation and keeping militarized equipment out of the hands of civilians primarily provides a greater civil protection against shootings/stabbings than ownership of body armour would.
Now, to not be objective for a second, i think real life is more complex, but empirically, given the relative differences in homicide rates, i'd say the American case at least appears to be starting the argument on the backfoot :)
Meanwhile, there's a tanker militia not far from where I live that practices regularly, and doesn't really bother anyone.
I'm fairly certain that there have been no tank related homicides in living memory, and the only two tank related crimes I can find news reports of involve a tank being taken from an army base for a joyride, and Killdozer, which injured no one (discounting the operator committing suicide), and was home-made anyways.
The thing about crime is that criminals instinctively want to hide what they're doing. Handguns are about a million times easier to hide than a rifle, or even a sawn-off shotgun. Having this bulky, visible weapon hanging off of your back is an automatic deterrent to crime.
[1] http://www.sandiegouniontribune.com/lifestyle/people/sdut-ta...
Isn't assault the quintessential thing that we have police around to deal with? If we didn't have any reasonable expectation of it then we'd be paying for a lot less law enforcement.
But empirically, i'd observe a couple of things in the Australian context:
a) Assault may be a continuum, with stabbings/shootings on one end, to the point where, as I said, almost no one reasonably believes themselves to be potentially shot/stabbed. (almost no one reasonably believes they'll be assaulted, either).
b) When people are assaulted or violently attacked, its almost infinitely more likely to be by someone intimately connected with them in their domestic or everyday environment, or in the context of drugs/alcohol. In that context, body armour appears to be to most people equally silly.
c) By far most police's time would be dealing with other matters apart from primarily preventing assault: case investigation and handling, property and vehicular theft, burglary, drug related offenses, traffic (including crashes, random drug testing, etc), crowd and pedestrian control (which COULD be stretched into preventing assault in context), suburban and domestic disturbances (which again, COULD be stretched into preventing assault in context). However, even in those cases where it could be stretched into preventing assault, the notion of appropriate use of body armour (or being exposed to stabbings or shootings in such a context) would be seen as relatively absurd.
Like wise in Germany senior business men have armed guards as a result of RA / baader meinhof.
Politicians also have well founded fears of nutters of political extremists trying to attack and kill them
[1] http://www.dailynews.com/2015/05/04/american-police-kill-civilians-at-a-shocking-rate-compared-to-other-developed-countries/
[2] http://time.com/4404987/police-violence/
No one has any reasonable expectation of being at risk of being shot/stabbed.
The only reason, therefore, that you would wish to have access to something like bullet-proof clothing or ballistic protection is that you foresee it likely you will soon be in a situation whereby you will be shot at.
About the only conceivable situation that you are likely to be shot at is if you forsee yourself or are planning to be engaged in some type of violent action against a police/military force.
Therefore, the only people wanting bulletproof clothing are those planning violent action against a police/military force. And since no one else who is deemed "socially sane" has any desire to own such a peice of equipment, banning it comes with the two benefits of not curtailing normal citizen's freedoms, while adding an illegal thing/signal to the kind of people who do or would plan to do bad things.
Edit: I realise there is the additional possibility that the person seeking body-armour sees themselves involved in gun-fights with other gun-toting individuals/criminals. Even amongst the criminal classes (and certainly amongst civilians), that is seen as almost an equally preposterous/rare idea as gearing up to take it to the police...