the calculation for child support is sooooooooooo ridiculously complex now
it's not just based on income
it takes into account the amount of time each parent has the children, a set amount is deducted from each income for living expenses, then the rest is pooled to become "family" income. that is then divided into the percentage that each parent has the children, and if it works out that one parent has more income than their percentage of time with the children, they pay maintenance to the other. it also includes other dependents

so, if for instance mum and dad have 65/35 shared care for mum/dad. after income is calculated for them both together it comes up to 100000 (50k each), dad would have to pay mum maintenance as he would be deemed to be earning more than 35% of their combined income and has to make up her income for the extra care she has

it is a LOT more complex than that, but that's the basis of it

if, as is the case in Ahurani's case, one parent has absolutely no income, if they had the same 65/35 split, mum would be deemed to have more than her 65% of the shared income, and would have to pay to dad

it's not ideal - too many people are working out how it's calculated and some of those people that are less inclined to want to support their kids are finding ways to get around it (like having their partner work and earn all the dollars so they don't have to pay anything)