I was thinking about this after seeing the BBC interviews.
It's easy to see why a family with substantial mortgage and 2 lots of preschool childcare fees would feel they struggled with 40-50K income. And interest rates are low at the moment so it could get worse. This is worst for people with children under 5.
Would keeping the WTC childcare element help? (that tapers off pretty quickly with income). Then the help would be there for people who don't earn enough to cover childcare costs, if the govt is so determined that they should work it can subsidise people who are effectively doing it as a hobby/ to keep career going.
The alternative is to admit you don't earn enough to pay someone else to look after your kids and do it yourself (i.e. SAHM or SAHD or combo) until one of them is at school. But that is a risky thing to do in (middle class) professional type jobs, to take a break, as you might never get back in.
Has a problem been created where previously families who would have just managed on one income with no childcare, can't now afford that without benefits (perhaps due to rising house prices since 1997) to enable the 2nd partner to work profitably while kids are young. And now the expectation is that mums will go back to work, you almost need an excuse not to put your child into Ofsted approved EYFS childcare, we are stuck in a kind of middle class benefit trap.
I think it's the preschool childcare thing that is the pinch point, that is the few years when people are most reliant on the TC, in usual circumstances.