the girl wasn't at fault here at all. anyone who says so is trying to jump to the conclusion of banning firearms "to protect the innocence of children".
this incident was in a controlled gun range, and it can be easily assumed this was her first time with a gun, or at least a fully automatic SMG. the instructor is at fault for hardly teaching her how to handle the gun. she probably held the trigger down when it was on semi-auto, just like she did when he switched it to full auto, so she couldn't have expected the recoil. on top of that, the instructor decided to switch the gun to full auto without telling her beforehand, so she likely assumed he had fixed something on the gun to let her fire again. by the time he had started telling her it was on full auto, it was too late.