*Privatise the (former) CSA and let debt collection agencies get on with the job.
If absent parents knew that refusing to contribute financially to their offspring could result in credit rating penalties, deductions of earnings court orders, etc some success might accrue.
I also advocate use of vouchers instead of money, because I read that fathers particularly are resentful to contribute as they only see in black and white.
They refer to paying money 'to the ex partner' and not 'for the children', as if their ex partner is greedy and taking the cash as surplus for spending on handbags and lattes. Not realising the contribution is absorbed into the ex partner's bank account allowing them extra overall to afford childcare costs.
Vouchers for school uniform, school meals, school trips, all the things that child support is supposed to contribute towards. Unfortunately a black market could arise from that I know, as it did when I used to receive the Healthy Start vouchers as a lone parent a few years ago. People were buying goods other than the stated milk/formula/fresh fruit and veg and just using the voucher as a discount off their total shopping bill, or the £3 vouchers were being sold to friends instead.
My children's father hasn't seen or spoken to them in 3 years now. He stopped visiting when I could no longer accommodate him at my house or afford his fuel costs to visit. He has been selling specialist goods on eBay for years and makes hundreds sometimes a few thousand every month, but as he signs on for benefits, only pays the minimum £5 a week for both kids.
I never asked him for money, and wouldn't. My wages and tax credits seem to cover living expenses although I'mnot looking forward to what I anticipate to be the more expensive teenage years, but then I live a fairly frugal life with no recreation subscriptions, car, socialising, smoking, etc costs.
I have emails from him saying he is going to fake a medical in order to receive some form of disability benefit, and he did it too, so I know he will never contribute voluntarily for the rest of their childhood.
What irks me lately, is that if my new partner ever lived with us, he would then effectively be financially supporting my children via pooled 'family' money, which is unfair on him, and that would probably spring me into action should it ever be the case.