Funny how you put it that way. I went to my favorite range last weekend with my younger brother. Both of us have considerable shooting experience with a wide variety of handguns, long guns, and select-fire weaponry as firearms instructors. Three shooting lanes over are three women and their teenage sons (sagging pants), shooting a rental gun for the first time. One of the sons draws a Glock 17 from his sagging drawers and points it horizontally like he walked out of a Spike Lee film. He fires, misses the target and shoots the target in the next lane, meanwhile his mother and his white-trash girlfriend (who is at least 30 yo) are recording him shooting with their iPhones. I tell my brother that I'm going over and put an end to this nonsense. When I speak to the one mother, she tells me that she's thinking about buying a Glock for protection and giving it to her son. Clearly, he's not anywhere near 21 years of age. I give her a little friendly advice, tell her to stop her son. She taps him on the shoulder, I ask to see the gun for a minute, drop the magazine, rack the slide, and take it back up to the rental counter. When I get up there, I see that both of the woman's sons are under 18 (their Ohio Driver's License is vertical and has a red stripe across the top). I informed the "range officer" who is monitoring remotely via several closed circuit cameras that the mother was not properly supervising her sons.
It seems that this type of situation can and does happen everywhere, even at some of the better managed ranges.