First one, they should have both had eye protection, the dad needed ears. But my dad started me shooting at about that age. Single shot .22 rifle and his Ruger Mk. 1. (no eyes and ears back then, no one thought of it). But nothing wrong with starting on the basics of safety early.
The second one, the guy is a jerk and should be horse whipped. All he did was teach her to be afraid of guns.
Third - I started my step-kids around that age. I didn't have they shoulder the gun like that, I had them tuck the stock under their arm and I had one hand on the buttplate and one supporting the fore end on my .303 Enfield, the 7x57 Mauser, and the 6,5 x 55 mauser. I also loaded up my front stuffer shotgun, .690 patched ball on top of 80 gr FFg. The boom, smoke, push, and the BIG hole it made made the impression on them that I wanted.