not to mention that a full auto weapon is very very very hard to use well.
I've got a couple myself and have been shooting things like them since I was about 8, and have never found this to be the case, especially with the pistol caliber guns. Hell, my kids were shooting my MP5 at 5 years old with no troubles, so they cant be all that hard.
One thing I've found over the years with owning and shooting select fire/full auto guns is, there are a lot of people who claim to be "trained" in their use, who have no idea as to what they are doing with one in their hands. A lot of these people were supposedly combat vets too. They all talk a good show until you get them out shooting, and then their skills seem to have wandered off.
Once you know the technique, and its very easy to learn, if the student is willing, you can shoot pretty much anything with little trouble and good results.