The impact of a substantial paid maternity leave goes way beyond the working women and their families. If such benefits were to be removed, it would decrease the number of women in the workforce. Removing a significant chunk of the workforce is not going to help the economy. And typically, it's going to be the people in the middle class who will actually be the most impacted and will be forced to quit or be put in a position that they end up quitting. So basically, we are talking about removing highly qualified candidates from the candidate pool.
In even greater proportions, it will affect the birthrate of the country. A lot of women will continue to work but will end up having fewer children. Either they will make this call or they will be forced to delay having kids till the choice is no longer in their hands. Look at Germany for instance. They are suffering from a declining birthrate to the point that they are forced to petition people to immigrate to their country. (https://www.reuters.com/world/europe/germany-needs-greater-immigration-avoid-labour-shortages-minister-2022-01-11/) One of the biggest reasons for this is the lack of support system for working moms over there.
Also, the whole point of taxes is to use the taxpayer money for the maintenance and betterment of societal conditions and structures. The kids who are able to have the advantages of having a mother who was paid fully during her maternity leave would enjoy a better socio-economic environment and this would translate into more qualified adults in our workforce 20 years down the line. Those very adults would be paying taxes that would help us when we are senior citizens.
As for the duration of the maternity leave, the recommendation comes from many agencies after decades of research. UNICEF is one of them. The first year of a child's life is where they need the most support just to stay alive. Infant mortality rates are the highest in the first year of the baby's life. It is also the period where children bond the most with their parents. It would have a very direct impact on how mentally stable the children grow up to be.
Taking a year off work is not an easy decision for anyone. For a lot of women, this is not even a choice. I personally know women who have to take extra shifts at work just because healthcare is so expensive in their country. Also, families come in all shapes and sizes. For a lot of the families, the woman might be the primary or the only income provider. How does pushing her family below the poverty line help the economy in the long run?
And why does this argument of taxpayer money only apply to paid maternity? I could make the same argument for paid disability leave seeing as most of us don't get to avail it.
In your post, you have talked about conceding to the wishes of the majority. While that has its own slippery slope, by virtue of that very argument, doesn't a paid maternity leave model benefit the majority? The demographic might be skewed in armed forces, but in most other fields it is more balanced or gradually becoming more balanced. Paid maternity leave will benefit the women who work and the families of those women. It doesn't just benefit the wife, it benefits her husband and her kids too. It benefits the single mothers also. If an argument has to be made, it should be for having a better paternity leave in place. And that is already in motion. People are fighting for that and slowly winning. Countries like Sweden have a 1 year parental leave policy. Tech companies are pioneering this change as well. (https://www.businessinsider.in/tech/news/google-increases-parental-leave-policy-to-nearly-6-months-and-adds-more-vacation-time-for-employees-in-a-boost-to-wellbeing-benefits/articleshow/89166239.cms) We should be championing that cause rather than a regressive approach of removing or reducing the paid maternity leave model.