Every time parents are arrested in the USA (and everywhere else) for committing a crime, their now unattended minor children are handed over to a social services agency, and they are cared for and protected. Tens of thousands of times each year in the USA, this happens. It's one of the reasons that we hire social workers.
The progs have conflated this to be 'unusual', when in fact, it's completely normal and done in the course of business for the criminal justice system. Crossing any national boundary in the world without permission is illegal. It's why there are passports and visas issued. My personal passport is filled with visa stamps that attest to my legal status while I visit countries INCLUDING MEXICO. Failure to follow the law would mean that I would be arrested and my actions would be evaluated for adjudication. If I had children in tow, they would not be placed in the cell with me ANYWHERE.
This argument that the left perpetuates is so stupid on its face as to be literally incredible. Yet still they promote it.