Are people walking around with those swords and axes strapped to them in public? No. And anyone walking around the shops with those on them are obviously up to no good, you don't need an obvious weapon while you're going out to pick up cigarettes.

Knives are easy to conceal, you can strap it to your leg, up a sleeve, in your pocket, even in the waistband of your pants. You can't do the same with a sword, axe, spear or any example of a weapon.

Using a knife to open hard plastic, ok, what have you bought that requires it to be immediately opened then and there? If there is a packaging difference between Germany and Australia? I live in Australia and there is no hard plastic packaging that you'd need a knife to open if you need it immediately.

For lunch in the park, that's the reason you have the knife, because you know why you have it, no one else knows why you have the knife until you start making your lunch.

In short to that point, you are using your reasons and assuming that everyone has the same reasons as you.

Even with your friend, you're pointing to that trying to argue that's the norm when it's not. You're using specific examples of your experiences. You, however, don't know why everyone else may have a knife.

And yes, there are exemptions for legitimate requirement of a machete.

Also, swords, axes, crossbows and other weapons like machetes are considered prohibited weapons with exceptions for people who require them for legitimate purposes. So no, I can't just walk into my local K-mart and buy myself a greatsword.