I agree that in most cases it should be easy for a single mother to get money for her child from the father.
However, a friend of mine may or may not have a son. His ex split with him before he was born, she'd been cheating for most of the relationship. She let him see the baby occasionally if he came to her house to do so, until when he was about 18 months old when my friend got a new girlfriend (I can't see an issue, she's a nursery nurse!, and the girlfriend didn't have to be present for him to see the child) , subsequently she refused to let him see the little boy who is now nearly 3. She regularly changes her number, so she can call him when she wants to but he can't call her as her number keeps changing so arranging contact is nearly impossible, particularly as when he can get through to her and she says yes and agrees to meet him somewhere, she always cancels at the last minute. He hasn't seen the boy once in nearly a year and a half. She frequently changes her mind on whether or not he is his and refused money per month when he offered it, preferring to go to CSA who said he had to pay 40% of his low income (approx £200 a week) despite her having refused to put him on the birth certificate, including arrears (out of his control, he moved house when they were first sending letters and didn't know about it until they found his new address). He was told to contest it he had to pay several hundreds of pounds for a DNA test.
Why should he have to pay when she refused money off him so that CSA would sting him, she won't let him see the child and it's not even certain that he's the father?
We also have our own case, where dp got custody of my dsd last year, his ex was unhappy about ss moving her from her, so made a CSA claim when she found out it was going to happen, when there had been a private arrangement between him and her, and between him and his other ex for his other 2 children. CSA contacted the other ex who jumped at the opportunity to join in and said she would like to make a claim too. They sent him an amount to pay based on a week he covered for someone else and earned £80 extra, so were trying to overcharge him massively, and they put the amount up when they found out dsd 3 lives with us- this nearly crippled us as I'm a student nurse and so only get a small bursary- we didn't qualify for benefits like housing benefit , yet what we had barely covered rent, bills and food and dp had to pay to travel to work which was also not taken into consideration- how they expected him to to support and house a child on the amount he was left with I don't know (they didn't know I existed so for all they knew he could have been left with only £120- 140 a week plus I think it was £150 tax credits a week) Our rent is £825 and bills come to nearly £300 a month as we have storage heaters and barely any insulation. (and no we don't have unnecessaries, we don't even plug in our TV to the airial to avoid needing a licence and don't have a car etc)
He got made redundant (they were kind and didn't fire him because he hadn't been there long enough for redundancy pay) because he missed work a lot with stress and not being able to afford the transport and DSD often needed him home due to problems she has. So for the past few months he's been on carers allowance as DSD who lives with us has a disability. But he's desperate to go back to work, but apart from how difficult it is to find something that would mean he could be home when DSD needs him, he is terrified of CSA trying to take so much that we can barely manage- we scraped by due to my bursary... DSD who lives with us, mum doesn't pay any maintenance either due to not working, so we don't have any money from her either. We can manage much better and have some extra money to buy DSD1 and 2 school stuff and clothes to contribute now as we get housing benefit now, we offered her this in cash instead but she said no she's going through CSA.
DSD 1 and 2s Mum can't possibly need the amount CSA said, she and her husband (him and his kids live with them and their mums other kids too) have gone on two weekends away already this year. That's a pipe dream for us!
What he want's is to be able to afford to pay a reasonable amount, whilst working, without DSD 3 suffering and going without the basics because she lives with us and he has to pay for the other kids, who are always complaining of being bored down the pub while Mum and husband go drinking every Sunday... nice to know our money was funding their habits while DSD had holes in her clothes and not enough for dinner!