This is in large part thanks to how suburbs are effectively no different than a ponzi scheme:

https://www.youtube.com/watch?v=tI3kkk2JdoI

Suburbs are not financially solvent, because they attempt to have the same level of amenities as an urban environment, all while being low density. This combination of low taxes revenue, with high maintenance costs means that cities have to constantly expand their suburbs or risk going bankrupt.

And it gets worse, because the infrastructure that gets spammed for these suburbs are funded with federal programs but the maintenance is put onto the city, and the maintenance costs don’t really show up until 20 years after the infrastructure is built. And when that bill comes, it far outweighs the tax revenue that an area makes. So to go back to being “solvent”, they spam more suburbs.

It’s a self feeding cycle that is not sustainable, financially or environmentally.