It's about choices
I agree the mother in this movie has faults. She has a issues that need resolved but it is not the mothers fault her daughter makes bad choices.
As a mom of three teens I feel the mom made the best choice for one night in jail. I've heard that before. It puts a scare into the kid. It's a wake up call. Tough love. The child won't listen to the parent so let the child learn the result of disobedience in the real world. Behind bars.
Sadly this spun things out of control. I my self as a teen spent time in a place like Northside profiled in this movie. The place I was in was actually shut down less than a year after my release. It wasn't run properly and often left in hands of uneducated workers who had place keeping eyes on troubled teens.
But the place I was in did open my eyes and I believe it saved my life.
This teen grew out of control a long time before she broke the law. The mom herself had issues and ignored the warning signs but in the end this teen made a bad choice and felt the consequences.