With respect - I am a man. When I was not the primary carer of my kids I paid child support. I disagree that "hardly any fathers pay". The kids now live with me..... Their mother doesn't pay a cent in child support.
Sadly, the system can only do so much. Especially when the payer is self employed it is difficult to get a good result from CSA. But that isn't the fault of the system. It is the fault of a parent avoiding their responsibility.
In my experience, they do investigate the can order payments BUT enforcement is impossible when for example a parent would rather declare bankruptcy than pay