The only reason the Republicans defend the family separation for immigrants is that our politics is a team sport where each issue is merely a point we score/defend for the team. We don’t evaluate each issue on its merits. Because the need to maintain the dominance is more important than each issue, if you disagree with your own team on any given issue, you are seen as a traitor by your own friends and families. As this is intolerable by normal humans who prioritize relationship over truth, even an obviously unethical policy like this family separation of immigrants becomes a huge, national fight, wasting countless hours of millions of people and airwaves.
If we had direct democracy where we vote for each issue independent of any parties or politicians, this issue would have been a no-brainer for the vast majority of Americans. We wouldn’t even be arguing about it.
In this manner, the majority of political issues we debate about are just symptoms of our broken political system, i.e., representative democracy.