Dress code or education whichs more important

My son was given a lunch detention on the 3rd weekend of school over pants that he wore the first week.. The policy says no sweats, joggers, etc.. One month or was no jeans then the next it was okay for jeans, no hoodies, then next hoodies are okay... As a mother of 3 children I don't have money for indecisive policies... I'm sure I'm not alone, so I feel that as long as no holes are in the clothes, no sagging,no to short clothes they should be able to dress appropriately. A teacher toldy son he can't wear Nike either, how unfair, what's important? The fact that he is in school or his clothes? I believe a solid dress code would be khakis and polo shirts or just what I described above.... No one has money to throw away, as parents we just want our kids to feel good and be comfortable while getting an education. These kids stand outside for busses in the winter and can't wear sweats to stay warm, thisakes no since... Who agrees?