Well, the median price home in SF is $1 mil. So how is a firefighter supposed to buy a home; send his/her child to school and do all those other things we do in life on $65k.
(Your figure of 1/2 of 175K=87.5 K (salary and benefits) Benefits are about 25% of the total, with the remaining being salary..roughly $65 K before taxes which in CA are big factor. The taxes alone on a $ 1 mil house are nearly $12k/year)
I realize $65k is a great salary in most areas of the country, but everything is relative.
Who says SF firefighters actually have to live in SF?
If the city wants to make residency a condition of employment, the city can pay them more.
Otherwise, they can live further inland where real estate is less outrageous.
United Airlines mechanics at SFO live several hours east and charter buses to take them to and from work.