Children being ripped from their families at the border?
1. They are separated to determine if the people taking them across the border illegally are actually their parents or some kind of human trafficker going to sell them as sex slaves to some rich pedophile.
2. No separation occurs if the crossing occurs legally. If they simply present themselves at one of the 18 legal crossing checkpoints, no separation occurs.
Back to point 1, human trafficking and smuggling is a HUGE fucking problem. Many children are kidnapped solely because having a child with you gets you a free pass in to the USA. Whenever someone crosses illegally with a child, there's no way of telling if that child is actually theirs, or if the child was kidnapped for an insurance policy in case they were caught, or if the child was kidnapped and is being smuggled as part of a human trafficking ring to be sold off.
The separation MUST occur to find out because if the child isn't questioned away from the "parent" or "hostage taker" whichever it may be, the child is not going to tell the truth. They will be intimidated by the kidnapper who will have told the child they will be killed or their parents killed if they do not swear that the kidnapper is their legal guardian. Once they are separated and the child can be put at ease, given food, and water, gets to sit and watch cartoons in a comfy processing station, etc. they will be more likely to overcome any fear they may have of the kidnapper and tell the truth. Especially after being questioned multiple times about things like how long they have known the kidnapper, where they were born, how many siblings do they have, etc. They can cross answers with the kidnapper even if the child is too scared to tell the truth and see if the stories and answers match up.
Of course nobody will bring this obvious point up in the seven illegal immigration anti-Trump threads.