[econner]

In San Francisco public housing projects are funded from fees on new development. In 2016, voters approved Prop C which increased the affordable housing requirements to 30% of the total units for a new project. A combination of factors -- rising construction costs, high land value, big fees (such as Prop C), onerous approval process, etc has led to the number of new construction permits being applied for dropping significantly.

That decrease has led to the city only getting funding for about 240 units of affordable housing in 2018 - 2019, whereas from 2014 - 2016 the city produced 500 units of public housing per year. [https://www.spur.org/news/2018-11-08/how-has-san-francisco-r...]

This is a long way of saying that the market affects everything. Even if we decide to build public housing that housing is not immune from market effects like expensive land and big construction costs. If it's more difficult, and therefore more expensive, to build market rate housing then it's more difficult and more expensive to build public housing.

For example, in the Mission no new affordable housing has been built in, according to Supervisor Ronen, close to 10 years. There are 7 projects in the pipeline, but none have broken ground [https://sf.curbed.com/2018/4/24/17276152/affordable-housing-...]. Long approval processes and constantly increasing construction costs are partly to blame.