I believe the focus on the expired laws is based on the assertion the effects of those laws are entrenched in their communities still. In SF, historical redlining is still obvious despite some gentrification in much of the southeast and the area around Van Ness north of Market. In these areas, things like smaller (cheaper) units, poorer infrastructure, and less business development perpetuate the segregation brought about in the years of redlining. Social norms further set up expectations about who should be living in certain areas, see the recent incident over a white woman challenging a black man's home ownership in Pacific Heights (rich, white neighborhood).