That's the sad truth. A someone posted earlier in this thread - if an event like the Sandy Hook shooting doesn't effect change, then not if anything ever will.
I remember seeing an interview President Obama gave where he said his biggest frustration with his time in office was his inability to change/strengthen the gun laws. It was shocking seeing the President of the most powerful country on Earth looking defeated by the knowledge that he is powerless to change it. How did the NRA get so much influence?
I saw the same interview and thought the same thing! 7 years as President and only 1 thing he appears totally unable to do anything about. But like you say how did they get so much influence? Is it an urban myth?
Surely the whole point of a Government/ President/ Prime Minister etc... is that they are at the top of the country - they run it. Everyone else is below them in terms of the Laws of the land and the economy. The simple fact is the Government DO have the power to change things, but they are scared of the reaction because out of 300 million people in America, probably about 3 of them have sane views on guns. Some of the stuff you read on Twitter (replies to Piers Morgan who is actually spot on about the subject) are crazy.
Obama has been a sitting duck as president since is 2nd year in office. Bush left the whole Country in a mess during his years as president, with 2 wars going on, high unemployment and the country falling into a deep, deep recession. Obama took office and could not turn the tide quickly enough, so the democrats lost the majority in the house of representative, meaning that he could not pass the laws without needing help from republicans.
He has passed a few laws that will help in the long term, like the health care coverage, but there are too many things that still need sorting out.
As far as gun laws are concerned, the NRA is a very, very powerful organization. They have most of the wealthy elite backing them, so getting any laws passed is going to be a tough sell. Having stricter background checks will not stop people getting hold of guns, only way to stop gun violence is to make owning them illegal, which is something that's not to happen