In part, the reason other countries don't have the same high murder rates is because of the prevalent gun culture in America.
Not only is that unsubstantiated, it's simply untrue, based on all the world's data taken together. You don't have any evidence at all that shows prevalent guns or gun culture (which I admit that we do have here, I'm a member of that culture) turns into murders. None. If anything, taken all together, the more the guns, the fewer the murders---but that's not as precise as saying, there is simply zero relationship between the two.
iow, there's everywhere from basically zero guns (Japan for example; we can't include Monte Carlo because it's just a city that's also a country, and if we study cities that's a different ball of wax), to what we have here in America, almost five guns here for every four Americans. Civilian owned and controlled.
And the murder rate is basically the same through the whole range. It definitely does not rise with more guns, but it can't be said statistically to decline with more guns either, the slope or coefficient is calculated as slightly negative, but it's statistically insignificant, which means we don't reject the null hypothesis, which is that the coefficient between civilian-owned guns and murder, is zero. Worldwide, the murder rate depends upon something entirely different from how many civilians have guns.
That's why you don't tend to see mass shootings in the UK or Australia etc. You're not likely to get a Columbine or a Sandy Hook where guns aren't so readily available to most citizens including automatic weapons. In order to own a gun in the UK you'd need good reason for it.
I know. But we as a nation believe, and this is expressed in our Constitution, that it simply being a human right, is all the reason any of us need, and it is also, an indisputably good reason.
There seems to be some odd thinking on here that because we don't allow the average citizen to own a firearm it somehow means we don't allow self defence both in or outside of the home which is baffling as of course it's allowed.
Of course everybody believes in the right to self-defense, unless you're a murderer or a rapist or other violent criminal yourself. When your life is demanded of you, by either man or beast, you will exercise that human right, of course you will, everybody will, everybody does, and most everybody almost unquestionably accepts self-defense as justification for being violent yourself, up to and including lethal force against the bad guy.
But we recognize the difference between lip service and real teeth. Our Constitution purports to protect our human right to self-defense, with real teeth. You all, and all of our democratic allies, like Canada, pay it lip service, but all your teeth have fallen out, and you're only "gumming" the right, in your law.
Your preparation to defend yourself involves improvised weapons, because you're going to need a weapon, whether improvised or real, if you need to defend yourself. Americans by contrast, get a gun. Then we carry. Then we get another gun, or a better gun, and we carry. We prepare to shoot, if we need to protect ourselves.
We recognize the right to defend yourself, your family, your neighbors, and any other innocent person against attempted violent crime or anything else threatening life and limb, and we recognize that the lawful exercise of your right, involves weapons, if you're serious about defending yourself.
It's far more unlikely that someone over here is going to be breaking into a home or threatening a person at gunpoint is the difference.
It's also far more unlikely that you'll successfully defend yourself, all other things being equal, if your access to superlative weapons is restricted by your own government.
The gun culture isn't the only reason of course but it's a fair chunk of the reason why.
If a government restricts the sale of bubblegum severely, then of course, you're going to see a decrease in the bubblegum stuck under public benches and on public railings. But gum doesn't play much of a role in a typical successful self defense. But if it ever did, and if you had had some bubblegum, and because of that, you were able to save your family from a bear attack or something like that, then you'd too recognize the restriction on gum as directly trampling your human right to self-defense.