In HS, when you are selected for a team and wear the uniform you are representing more than just yourself. You're representing the game, your teamates, your coaches, the school, and the community. Members of the community want to look at you as being fine scholar/athletes who represent them. They want to be proud of you and by implication themselves. Wearing the complete uniform properly, being well groomed, taking care of your grades, and being a good sportsman on an off the field is how you go about being a good ambasador for your community and your school - it's not how many games you win or titles you obtain. It's very different than playing for your club team. Coach, maybe your kids don't understand this yet. If not, then tell them why your requirements are important and let them know what will befall them if they choose not to follow your requirements. Then boot them if they mess up again.