We tend to forget that the separation from Britain was prompted primarily by commercial interests and amended, after the Confederation proved unworkable, by a more idealistic group committed to the primacy of the individual man (children slaves and women not included.)
Since 1789, there has been slow progress towards realizing the rights of persons in the law, even as the rights of property (real and progeny) persist. In part, the primacy of property rights, which are what define, as GWB proclaimed, the ownership society (a society that relies on the right to own as a reward for fulfilling social obligations —i.e. parents get to own their children as long as they provide appropriate care and feeding and, if they don’t, the children will be taken away and given to someone else as a source of revenue, as the alien migrants crossing the border on foot are discovering, along with the rest of the USA who are not part of the 475,000 whose children have been rendered to foster care). The reason judges were prepared to interrogate small children is because it happens all the time in juvenile court. Where the current Administration went wrong was in not providing the parents with free legal assistance so they could make the case that they are not being irresponsible in taking/sending children to a safer land. That all PERSONS within the jurisdiction of the Constitution have civil and natural rights that must be honored/respected by agents of government is a relatively new concept clarified by the SCOTUS during the GWB Administration in response to legal challenges mounted by alien persons who had been detained at Guantanamo and the black sites. Prior to that, it was only the children of aliens whose entitlement to a public education had to be honored, because, of course, children are not citizens and their education is a societal, not an individual good. After all, the reason we mandate that parents allow their children to be educated at public expense is because we know from historical experience that many parents would just as soon put the children to work for them at home, on the farm or in the shop. The free labor of children has long been preferred, if only since the early experiment of employing women in the textile mills of New England proved disappointing in that the women insisted on organizing their free time to advance themselves intellectually and artistically in order to make themselves better household managers.