55 years of republicans working to lower taxes and demonize public employees has had an effect, even in cities that don't vote republican. Our cities are starved of money for basic maintenance and to pay the best and the brightest to do public work.
San Fransico's sales tax (8.5%) is lower than the average Californian city (8.56%) and lower than the average city in many states, for example: Alabama (9.14%), Arkansas (9.43%), and Kansas (8.67%).
So it's definitely not accurate to say SF has "extremely high taxes".