We should also ban cars that do over 60 MPH because of how many people are killed by drunk drivers and teenagers that loose control of their vehicles... right? Same type of logic as you are applying to semi-auto weapons...
To be allowed to drive a car, even at 60 MPH, you have to do a certain amount of hours of lessons, sit and pass numerous tests, you have to provide a range of ID's, social security number and a range of other information. And this is just to get the license.
Once you have obtained your driver's license, the police can stop you and check your license and run a check on you, they can stop you and check your car, check to see if you are drunk or stoned and if you are, they can arrest you.
To purchase a gun in the US, one can simply attend a gun show and provide one piece of photo ID and that's that.. You can walk out with a semi-automatic weapon, no questions asked.
And it is absolutely legal.
Adam Lanza's mother believed the world was going to end so she was paranoid and stockpiled food, water and an arsenal of weapons in her home.
No one asked or check on her psychological state and if they did, apparently being paranoid does not warrant extra scrutiny before allowing her to purchase her weapons.
No one also thought or sought to ask or question the safety of those weapons knowing she had a mentally ill child in the house.. In fact, she even took her son's shooting, and no one thought to ask her why she would take a mentally ill boy shooting.
So I have to ask you Kittamaru..
Why do people (average citizens) in the US need semi-automatic weapons?