evidence: The phrase "kids in cages" has become a catchall for the Trump administration’s approach to immigration enforcement in recent years, to the president’s evident frustration. As he pointed out during Thursday night’s presidential debate, he didn’t build the "cages" — the Obama administration did. [...] Biden responded by stating, correctly, that the Obama administration did not systematically separate parents from their children at the border, a practice that generated such backlash that the first lady and Trump’s daughter Ivanka joined the groundswell of people who pressured him to end it. [...] Fleeing poverty, chronic violence and joblessness, the families also were spurred by smugglers telling them that children who cross the border could generally avoid lengthy detention and certain deportation. Those claims were accurate.