Society does intervene in the private sphere to prevent harm. Domestic abuse is simply the most obvious example but parents are also responsible in most societies for ensuring their children receive an education in accordance with the law. If a parent were to deny their children food when it was available, it would be neglect. If they were to deny them shelter and protection when available, it would be neglect or abuse. It is difficult to see how denying them healthcare, when available, would not fall into the same category.