That's just the way I see it based on my own mother and fathers experience with me. He always have me plenty of support so my mother felt no need to put him on child support. Like if he's being the kind of dad who ghosts on their kid I understand but if he's raising them and involved in their lives he should be already supplying them with resources. That's just how I see it
Might I play Devil's advocate for a moment?
Unless I'm misconstrueing what you are saying, the logic still applies. She may have had to take him to court, not because she was a bad mother, but perhaps because he was a bad father.
When my own mother took us kids and left my father, she was adamant she did not want the courts involved. She always told me my father was a good man and did right by his kids. She went to him straight up and tried to work out something between the two of them.
However, because she left him, to spite her, he didn't honor their agreement and pay anything for us. She didn't want to but she eventually got the courts involved. Then he just stopped working...
This was my father, who, up until then, I could only remember as being loving and doting on us kids, who was now purposely taking out on his kids the anger he felt for his wife.
You just never know.