It was also largely about maintaining 'racial purity' and enforcing 'racial integrity' laws:

https://encyclopediavirginia.org/entries/racial-integrity-laws-1924-1930/

I don't buy that the lower taxes were payment to the women for her unpaid labor. If 'American values' actually valued paying women fairly, there wouldn't have been the need to fight so ferociously for equal payment to women in other areas of the work force.

It had more to do with incentivizing people to get married. Regardless, most of the incentives and tax breaks that married couples used to enjoy have largely been voted down and rolled back by the very same right-wing politicians demanding that people should get married and have kids.