Seattle is a city, San Francisco is a combined city and county; it literally has a lot of functions that Seattle doesn't. Add a population based pro-rata share of King County’s budget to Seattle’s budget and you get something not all that much less than the budget of the City and County of San Francisco.
Also, California has realigned a number of what were previously (and are still in other states) state functions to counties, including some felony incarceration that would otherwise be in state prisons, so, even compared to out-of-state city and county combined functions, SF has more it is required to do.
Also, California has realigned a number of what were previously (and are still in other states) state functions to counties, including some felony incarceration that would otherwise be in state prisons, so, even compared to out-of-state city and county combined functions, SF has more it is required to do.