“In older or more rural neighborhoods with wide variations between houses the margin of error can get very high—particularly if public records are either inaccurate or not up to date.”
That’s a great point. In my city, San Franciso, you can seen brand-new high-end condo construction on the same block as some 150-year-old house that has had “deferred maintenance” for its last 140 years. Those situations confound the algorithms.
Your example is really complex—because the true value of the old house (defined as the value of the best and highest use) is probably the value of the land minus the demolition cost of the house.
:-)