My point was mainly that that kind of first tier city would attract those kind of people, not specifically that they should be targeted.
If you lived in a 2nd tier zone you shouldn't pay extra in taxes even if you're childless.
But specifically to your question, I do think that it's fair that childless people should pay more taxes, because having a stable population is a requirement for a stable society and single/childless people aren't doing their part.
That duty can be offloaded to parents with more children, but they should be compensated for that.
You can frame it whatever you want -- they pay more taxes, parents pay less taxes, parents get tax rebates, parents get higher UBI per child, the outcome is the same.
I do think that first tier cities leach and profit from the work of the parents, educators of the people who migrate there (and generally the whole area -- it takes a village to raise a child), profit from exorbitant property taxes so, I think the only way to solve this curse is higher taxes (if it's required) on those areas and subsidized living in less desirable places -- provided that those 2nd tier places produce competent citizens.