Actually, those guys have collected both tax data and spending data. They show very well that the older, poorer parts of cities universally collect more in taxes than they spend on services, and the surplus subsidizes the richer suburban areas. If you have any data at all showing the opposite, I'm sure they would love to see it.

Strongtowns is not some hotbed of liberalism. They guy who started it grew up on a farm in a small town in Minnesota. He is anything but a "liberal."