In Michigan if there is a separation, children go to the mother by default. Father must acquire legal representation to properly present a case why the children should be placed in custody of the father. In Michigan, this is commonplace. Men who fail to pay child support find themselves in jail once their bill accumulates over $2,000 no questions asked, regardless of circumstances if you can't pay during that FOC hearing, the only parent that leaves the courthouse that evening, is the mother. That's less than 2 months' payments at the rate my dad paid, regardless of reason or intent. Locking them up, mind you, terminates them from any occupation they may have had, effectively neutralizing their future ability to pay the child support.
I know a drug-addled unemployed mother who is considered better fit for parenting than the slightly less drug-addled, yet employed, father. Under the basis that the father was single, while the mother was dating (probably her dealer) another posterchild of addiction at the time of the last hearing for custody. I don't know the answer, but I think they rewarded the worse of two evils.
My father, an employed GM worker of 20+ years, with a house mortgage paid off, and a wife. Was paying my mother $280/week to support my sister and myself, while my mom struggled working 2 jobs sometimes 3 trying to fund a home for her kids as she got moved around due to unforeseen circumstances sometimes, and improvements to location or occupation other times... If father had custody, we would have had stable foundation, mother would have had more energy and time to get situated. My mother never put in effort to help my father attain any more rights or lenience from the FOC, so until I moved to his house at the age of 14, he got to see me and my sister twice a year. He had our names tattooed on his heart. He wanted to be a father, we were his purpose for existence, and made it abundantly clear that he loved us both with all of his heart.
Thinks aren't black and white. "Pro this" or "Pro that" is a 2-dimensional person, humans aren't 2D.