This is pretty great! This data is usually locked up in individual scraper-unfriendly county websites, sometimes behind a paywall, sometimes only by person, or

This is pretty great! This data is usually locked up in individual scraper-unfriendly county websites, sometimes behind a paywall, sometimes only by person, or even only by mail. And the data is often limited to parcel geometry, not building footprints. The other option is to use 3rd party services to purchase or lease the data. This data can cost hundreds of thousands of dollars for the entire US dataset.