The assessor's job is just to determine the value of the various sites. It is said that a group of locally knowledgeable people could sit around a table with a large map of the community, and they'd quickly reach a consensus about what is the most valuable site in the city. And then they could go block by block determining the relative value of the various neighborhoods. From that, a land value map could be derived, and likely it would get a few tweaks from the community.

As Bushwick becomes popular, because of better transit, or community amenities or whatever, yes, the unimproved value of the sites served by them go up. A school develops an excellent reputation? Up go the land values. (Some say that in most suburban towns, the superintendent of schools is the highest paid employee, in part because s/he can influence "property values" -- more precisely, land values -- more than any other single person.)

My first acquaintance with Elizabeth Warren came from a book she wrote about 2003, whose title was something like "The Two Income Trap: How Middle Class Parents are Going Broke" and in part it was from seeking the best public schools for their children, and paying a huge share of their income for it, seldom to be matched by single parents.