SF's budget doesn't contain $15B of money it can use for whatever it wants. Most of it isn't discretionary, either because of voter mandates or by federal/state government requirements and has to go to specific programs. A good chunk is actually city businesses (hospitals, airport, utility, port, etc.) which mostly break even.
SF was able to spend money trying to getting rid of RVs because it was living on emergency money from the state and shifting capital expenditure priorities around (capital expenditures costs are offset mostly by the asset you're buying, at least in the short term).
That emergency money is gone now, so now we're living in an era of budget cuts, though given SF's history, I full expect it to spend money recklessly and hope revenue turns around, but even they aren't so far gone to add $300M in operating expenditures to make MUNI free with no plan for a source of revenue to make up the difference.
SF was able to spend money trying to getting rid of RVs because it was living on emergency money from the state and shifting capital expenditure priorities around (capital expenditures costs are offset mostly by the asset you're buying, at least in the short term).
That emergency money is gone now, so now we're living in an era of budget cuts, though given SF's history, I full expect it to spend money recklessly and hope revenue turns around, but even they aren't so far gone to add $300M in operating expenditures to make MUNI free with no plan for a source of revenue to make up the difference.