Unfortunately there are a lot of Americas who are equally abhorred by the regular needless killings but they are powerless as the gun lobby are a powerful group, and supported by millions, many very rich and powerful.
This outdated "right to keep and bear arms", aye mibbie in the days of cowboys, is still seen as a democratic right.
Obama has tried to make significant changes and largely failed.
It is hard for most of the UK to even come close to understanding the mentality but it is so ingrained it's hard to see things changing, even with the latest horrific event.