Women are still in real life required to take by far the largest share of the caring burden and also remain very much overrepresented in those professions. In my experience, the availability of childcare is a much bigger issue than the cost of it. The availability issue is what requires both of us to take 4 weeks unpaid leave each summer, while also paying significantly more for various camps than we would do for childcare. We are far from unique.
We are extremely fortunate to be able to take that unpaid leave and also to be able (via flexible hours and blended working) to make up (with some difficulty) the gaps between the availability of childcare provision and retaining full-time jobs. Take away the flexible hours and blended working and we would both need to cut down to part time hours regardless of the financial impact. And regardless of the amount of money involved neither of us can consider taking a role which doesn't have the flexibility we require.
So let's not confuse the effect of marginal tax rates with the combined effects of a culture pushing most caring responsibility onto women who are consequently greatly disproportionally affected by insufficient childcare provision. One may disincentivise work (although as I've already said I very much doubt that actually happens) while the other actively prevents it (and is also responsible for the gender pay gap).
I appreciate that a site called askaboutmoney is completely the wrong place to say this, but money isn't everything.