Because of the very different history of the USA and the UK.... plus the geography and demography... we have always had guns as part of daily life for many people. At one time... or more precisely, for many years, it even made sense to have guns available to conquer the wilderness and the "fierce natives" (tongue in cheek)... and to defend the very idea of having a USA at all when King George was was trying to say we should remain a colony.
   Then came our sad Civil War, to determine whether "any country so conceived and so dedicated should long endure". By the time the Civil War ended, keeping guns... "just in case" was a common theme, and maybe even still made some sense.... but the technology kept increasing as the urbanization also increased, and the 'country folk' who moved to the cities to find work carried with them, for various reasons, the idea of owning guns.

.... So.. with so many having the idea that they 'ought' to have guns, the firearms industry found all sorts of reasons to support the idea..(big surprise?)...they used that one vague phrase in the 2nd Amendment to apply 18th century reasoning to 20th century conditions and now we have an entire organization, the NRA, existing primarily to protect a 'right' that never should have existed beyond about 1895.

What we have is a situation where FAR too many own guns... with a significant number of them willing to use their guns to avoid those guns being "taken away".... and others seeing guns as a means of settling arguments or committing crimes. With many millions of guns available, almost anyone can get them... legally, if they have not committed a felony--yet-- and illegally if the have a few dollars.

Thus, the very fact of 'bad guys having guns' leads to the stupid idea that "good guys" NEED them for protection, even as statistics show how seldom that works out.

So... you folk in the UK see the horrendous news stories and quite rightly wonder why we 'permit' such conditions... for the answer, re-read the above. Many of us despise the situation, but the solution is NOT... I repeat... NOT just a **simple** matter of passing laws and/or amending the Constitution. That is what it would take, but changing the mindsets necessary is as hard as rooting out prejudice & bigotry.... and IF such laws & amendments were passed, there would still be millions of firearms and stockpiles of weapons hidden away.

   The process is daunting. That doesn't mean I...or Joe Offer... or millions of others... have given up. We just see what we are up against.