That's a very important question as well.
The simple answer is because you have the tax department running the program. If your goal is to deal with poverty, you do not want to put the tax department in charge of solving a problem of poverty. If your problem is inequality between men and women, you do not want to put the tax department in charge of solving that problem. Their job is to raise revenue.
The secondary consideration--in addition to putting responsibility for that where it belongs, which is with the Minister for the Status of Women--is that when you deliver social programs through a tax instrument, there will always be a significant sector of the society that cannot access those tax benefits or is afraid for some reason to file a tax return in order to get that poverty relief. There may be people who have irregularities in their personal histories. There may be people who are simply afraid of the authorities as part of their cultural heritage. The list goes on and on. So the decision to deliver any social programming through the vehicle of a tax credit is a decision to cold-bloodedly plan to exclude at least 5% or maybe 8% of the target recipients from the program.