Haha, I think that was about the age when my brothers stopped letting her cut their hair as well. She'd either do it too short or too "conservative" or whatever, so they eventually got pissed off and one after the other went "That's it, I'm going to a hairdresser the next time.".
My hair has been fairly simple to cut, though. Just needed some trimming about once a year (she once cut 15cm, when she was supposed to cut like 3 - almost refused letting her do it again after that one), and I could've done that myself, except for the whole not-seeing-my-back-thing.