Need has nothing to do with it, people do many things they don't need to do and you don't see people pointing those out. Of course the type of weapon is the issue, it's something with less surface areas to hold which results in less control, add in the recoil of automatic fire to the child not holding the gun tightly enough and you have this incident. It wouldn't have happened if it was on semi automatic, she wasn't standing up and obviously inexperienced with firearms.
How exactly would you say then that you could lose control of a bolt action rifle mounted on a bipod in a seated position? No one is going to be in front of the gun so I wouldn't class squeezing the trigger too hard and firing to the side a bit to be losing control and once that round is fired it won't fire again until you **** it so even if the gun jumped in the air after you fired it, it couldn't just shoot itself.
The fact that many children in America fire bolt-action and semi-automatic guns without losing control and killing someone in America seems to be a pretty good argument as to why the type of weapon and 
firing mode does matter.