There are plenty of ways they could have changed the CSA (as it was) system to have much better enforcement.
Back when RP's on benefits were allowed to keep only £20 a week and the rest of maintenance was owed to the Sec of State the amount owed to the SoS got so ridiculous it was declared that something had to be done.
Despite all the options at their fingertips that government - and every one since who've done nothing to change it - decided to let people keep the money that the knew mostly wasn't being paid
There is no political will, from any party, to tackle the shambles that is CMS. It's not even down to the staff there either - when I worked their briefly I asked the person training me when we'd learn about certain powers (I happen to know about them because if my non paying ex) and the trainer didn't even know CMS had those powers.
I was told off for refusing a non-payer extra time to pay. Apparently refusing an extension was "aggressive and unnecessary" - not my manner, or my following process, that was all clarified to be fine, but granting an extension is normal - when he hadn't paid a penny for four years.
No party has touched it because there is, imo, still that mindset for so many people of women (and it is mostly men who are non payers) who end up as single parents being feckless and greedy. Until societal attitudes to non-payers change then political will won't change.