kids hair cut,

My son is 6. I love his hair in a foehawk cut/style. He on the other hand likes it cut so short that I can't do anything with it really and then he throws a fit when I can't style it. It's his hair and I try and let him choose what he wants done with it, but I always hate what he chooses. I pay $20 for him to pretty much get a buzz cut. Do you guys let your kids decide what happens to their hair? Or at what age did you. In just to the point where I'm not taking him to get one and he can just have long hair.