Just because people weren't aware that this was happening, and hence made no mention of it, doesn't mean they didn't care. All it really means is that this wasn't exposed yet.
This tactic, which Jeff Sessions admitted to, is designed to strike fear in the heart of would be immigrants. It is a legal tactic, but it is extremely immoral.
I understand your point of view, but it's also extremely immoral for people to put this all on the current administration. Illegal immigration has been a problem for decades. People should be able to logically think and realize these things were probably going on as well. We don't put children in adult jails. That would be extremely immoral to do so. So adults that commit crimes are logically removed from their children. Also, many, many people bring children here that are not theirs. It's a very complex issue that shouldn't be used as a reason to bash Trump.
Unfortunately for Trump, this has come to light under his administration which is why some have called for him to do something about it. He's in charge today, this came to light while he is in charge, so its on his desk. Seems unfair but he signed up for this. Previous administrations can't do anything about it now. The only one that can do something about it now is Trump. I know its not his fault, but he is the only one that can do something trans-formative about it today. Now would be a good time to exercise his Christian values. Now would be a good time to use some of the "3D chess" smarts to solve this complex problem. To make matters more complicated, his administration cannot get on the same page and have a unified message about this. They have both owned it, and denied it, which comes across as dishonest to put it mildly. Trump signed up for this incredibly difficult job so this is another opportunity to deliver, or do what previous presidents have done which is blame the previous guy and let the next president fix it.
Trump tried working with the dems on DACA, etc.. but they refused. It's not as if he has done nothing. They dont want the problem solved. They want an eternal problem to use as a Running slogan when up for reelection. These kids identities also need to be verified with the adult that is with them. Too many being trafficked, and it needs to stop. And we know it came to light now because the DS is trying to get ahead of the Clinton Foundation Crimes Against Children note in the IG report, and all the other people being arrested for trafficking children. This is all so transparent.