WHY DO CUSTODIAL PARENTS DENY THE OTHER PARENT ACCESS AT SCHOOL AND WHY DO SCHOOLS ALLOW THIS?

I have had several cases where the custodial parent has instructed the child’s school to deny the other parent access to the child at school. This is apparently based upon the belief that the custodial parent has custody during those times to the exclusion of the other parent. To my dismay, the schools cooperate in this denial of access even though there are statutes in this and many other states that specifically allow the non-custodial parent access to all education and medical information. There is no question that studies show that children do better in school when both parents are involved. What can be gained by this denial of access? Legislative action is probably needed to cure this type of conduct, which only serves to damage our children.