I understand it's going to hard but not impossible. Assessors can work together at the state level and identify owners with multiple properties and send them the extra tax bill or a way to dispute it. They have enough information about what we own and where we live.

Tax policies that require more than perfunctory policing are generally a bad idea IMO; tax evasion becomes a realistic option (everything from farming out properties to their extended family to "reside in" to avoid paying the higher rate to befriending assessors to have them misidentify you as a resident).

Policing is definitely possible, but I don't think the added cost and operational complexity make it advisable.