I'm not saying it's not worth considering that childcare is both parents' responsibility, himalaya. I think it is and should be. But personally I think society does also have responsibility for the next generation, and if that means subsidising childcare, that makes sense to me.
I'm not sure how it would work, so I am just thinking it through.
I do see your point about dad on 50k paying for childcare - because the household income would be high. But then, couldn't dad on 50k contribute a chunk of his tax to cover childcare instead?
I think that the problem with debating this is that the current situation needs sorting out from two perspectives - we need to sort out the domestic attitude that childcare is women's work, and we need to sort out the employment attitude that it's ok that women tend to get pushed out of careers (especially some careers), even though this isn't only about childcare. It's hard to think how to sort one problem without coming across as if you're dismissing the other one, but I don't mean to dismiss anything.
I think the current system is pretty inefficient, and that's a good reason to dislike it. It's maybe a bit like the attitude to education - people resist higher taxes, and we don't put enough money into early education. But it is then hugely expensive to provide remedial education to adults later on ... and yet that's what we end up doing in many cases. I wonder if childcare isn't similar, in that if it were sorted out at root - with funding easily accessible - then perhaps we wouldn't be bearing the costs that come with losing skilled workers.
I know this is dead biased btw, and I'm not suggesting childcare isn't skilled work (!) - just it seems a lot of people leave careers and don't get back to them, who really would like to.