The problem with presuming shared custody:

*Proving* spousal abuse and domestic abuse is nearly impossible and women are not believed. You have to have proof.

You have to have lawyers.

You have to have MONEY.

No one has money.

It leaves you parenting with toxic, abusive psychopaths.

OR

The courts funnel you into "mediation" which is a kangaroo court, but it's binding nevertheless. The mediator chooses his horse, not based on facts, but based on who he LIKES, and he might like the BAD GUY, your abuser. But abusers are CHARMING, and abused wives are sometimes not charming.

I suppose that would be better than having your children alienated from you, as the toxic, abusive psychopath I married has done to me. But lacking a lawyer, I lost my kids in short order. All he had to do was manipulate them into running away from home.

It's not hard to make teenage girls hate their mother.