> In Seattle, where the housing market is considered expensive, a 1.2m house only pays $7k in property taxes
Only if it has (a) an exemption or (b) an assessment well below market value. A typical house with a $1.2 million assessment will have paid over $10k in property taxes in 2022.
That would be option (b) in my comment. Washington State law requires assessed values to be 100% of "true and fair value"[1] despite the fact that they tend to lag market value.
In Seattle, where the housing market is considered expensive, a 1.2m house only pays $7k in property taxes