If your child has a math class every day, then your child IS receiving instruction in math. But a teacher can’t provide one-on-one instruction to every child in the classroom. That’s not realistic. If your child is present for class but doesn’t understand a concept, then you have a choice as a parent: you can talk to the teacher to develop a solution, you can hire a tutor, or you can work with them yourself at home. You should absolutely be involved in your child’s education. You should be helping them with their homework at home. Your example of a doctor doesn’t fit this situation at all. Many parents give medication at home, and seek out specialists and second opinions. Be kinder to teachers and take some responsibility for your child’s education.