The state does as much as they can with the funding they have. Sure, it's partly their responsibility to enforce and collect support. But it's also partly on us as parents to share some responsibility in the choice that we made to make the other person a parent to our children. Yes, it sucks. But it's reality. We can't just cry victim and whine about how it's not fair and all someone else's fault. We had a part in this as well.
And you don't just have to sit on your hands and wait. You have all of your options spelled out above, limited as they may be.

