I imagine it's tricky because value per square foot varies quite a bit in adjoining neighborhoods. And sometimes within a neighborhood. And neighborhoods aren't necessarily well defined geographically. And, some neighborhoods go long periods of time without any houses being listed or sold.
> value per square foot varies quite a bit in adjoining neighborhoods. And sometimes within a neighborhood
The quality or rather "reputation" of the assigned public school is probably the best predictor of this variance. The problem is that the school's reputation can diverge from the official grades, so this is difficult to quantify.
Sure, but there are other drivers that would cause different value per square foot. A house with 12 foot ceilings, granite countertops, stone floors, wainscoting, built-ins, high-end appliances, tile roof, and so on...could be 100 yards from house with the exact same square footage, and none of that. It trips up the Zestimates around here. Especially in areas with larger lots, where bulldozing the old plain ranch house and replacing it with a higher end house is common. The per-square foot values are very different.
Edit: also, near power lines, near water tower, on cul de sac, next door to elementary school, etc.
So the whole idea of "comparable sales" is shaky.