Why two identical houses end up assessed differently
Not corruption. Model drift, stale records, and errors nobody has a reason to find.
Owners who discover a gap usually assume favouritism. It is almost never that. The real causes are duller and more fixable.
Stale characteristics
The county's record of your house was created once and updated when someone pulled a permit. A finished basement recorded in 1998 that was never finished, a garage counted twice, a square footage taken from a plan that changed during construction — these persist for decades because nobody has any reason to re-measure.
Permits
Improvements get picked up when a permit is pulled. Neighbours who improved without one, or whose permit was never linked to the parcel, can carry a lower assessment for years. Your addition was caught; theirs was not.
Model boundaries
Mass appraisal works in neighbourhood zones. Two houses on opposite sides of one street can fall in different zones, with different rates per square foot, for reasons that had nothing to do with either house.
Prior appeals
A neighbour who appealed successfully three years ago may still be carrying a reduced base. Appeals are individual — nobody applies the outcome to the house next door.
What to do about it
None of these require you to allege anything improper, which matters: a filing that accuses is a filing that gets defended. The claim is simply that the records describe two properties the same way and assessed them differently, and that the difference should be corrected.