Maybe I misunderstood you, but I don't understand why there shouldn't be a consequence for not paying child support. Whether your underemployed or not there is no excuse.
@Sterling Archer gave me a good answer, but I've seen threads where people complain about getting money taken out their checks for child support too.
I think if we came up with a good alternative to the current system things could change.
Question. If both parent's are unemployed and homeless, should they both be thrown in jail? Neither is providing the child with accommodations it deserves.
There should be a punishment for child support but I honestly don't know what it is. Whatever it is both parents should be held to the same standards. I don't see how jail solves a problem for anyone except the state.
I think there should be a standard child support across the board. All single child situations are $200. Any additional child is $100. If you have more than one baby mom/ baby dad your total child support shouldn't total more than whatever the formula generates.
3 baby mom's means you pay $600. 3 baby dads means you receive no more than $600. 2 baby moms and 3 children = no more than $500. 2 baby dads and 3 children = no more than $500.
These babies should be get rich quick schemes. Both parents should have to pay for child care so both parents can work. If one parent isn't working there should be a punishment... still don't know what that would be (forced employment?.. scary proposition, i know). Maybe you can add to and edit the solution. Let's not get wrapped up in the $ amount, that can be debated later. Two heads are better than one on this.
*edit*
Solving this problem would be a lot easier if the kids were allowed to stay with the parent that's doing the best instead of the default being the woman always keeps the child. In the circumstance the man is doing better and he's a law abiding citizen who wants to be there for his child/children then he should be able to keep them. Same goes for a woman doing better than the man. She should get the child/children if that's what she wants.