Child support

So ladies, I believe I have an unpopular opinion. Please read the whole story before commenting.
My SO has a child from a previous relationship he's now about 21 years old. This relationship was about 2 months long she said she was on the pill so don't worry about protection, we got together and she came knocking on the door saying she's pregnant. He told her right from the beginning he didn't want a child ect.. and she decided to keep the baby and do it on her own (admirable but....). When boy was born she contacted and asked if he wants to see baby and be on his birth certificate, was again told no. Fast forward 7 years she decides she wants him on birth cert, goes to centerlink and suddenly remembers who her sons father is and has him put on the birth cert and have to start paying child support. I already have a problem here because she lied and got pregnant, lied to centrelink then wanted him back in her life and tried to use this to get it.
So changed jobs several times so has paid then not paid required child support. Kid is 21 this month and government is now garnishing $150 per week from his pay for owed child support.
Now I've been a single mum of 2 from a partner I was with 4 years, he wanted both kids but when he walked away he left everything about them behind, I never chased for child support because I was just happy he was out of our lives.
This one was lied to so she could fall pregnant, so tricked into the child, was upfront about not wanting it but had no choice. When she decided she wanted to get child support she went for it ahead had no choice. Kid us now out of school and presumably working and government still wants to take money from him for this kid. How is it fair for men? We fall pregnant they want it we don't they have no say and have to miss out. We fall pregnant we want it they don't they have no say and have to step up.
Just wondering if I'm the only woman that has a problem with this system?