I won't entirely disagree that it's fiscally regressive (most regressive tax policy in the country IIRC), but we're talking about the city of Seattle specifical

I won't entirely disagree that it's fiscally regressive (most regressive tax policy in the country IIRC), but we're talking about the city of Seattle specifically which tends to favor worker rights a bit more than the statewide government does. See: sick leave policy, minimum wage policy, etc.