The recommendation is to eliminate all tax provisions that essentially reward a couple for making sure that one of the parents spends a significant amount of work time in unpaid work activities, such as supervising children's play.
This puts a lot of pressure specifically on women. They are the ones with the lowest incomes, and it's more cost-effective for the family to make sure that it is the woman's work that is taken out of the labour force. This puts pressure on families, because a woman's energies can only go so far. There are only 24 hours in a day. At the same time, it detracts from the family's total financial capacity.
If you were to take all of the joint tax measures out of the tax system, you would have, if you did a 100% job—I just finished doing this simulation—it would put $25 billion per year more in the hands of women, and women would have disposable incomes of $3,128 more per year.
A tremendous skew takes place that basically cheapens women's paid work and treats their unpaid work as a limitless free resource that we all can draw upon.