Look, radical leftist politics in SF (or anywhere else) would be about:
1. corporate taxation
2. minimum wage at $21/hr or above
3. limiting investment in residential real estate
4. major investment in public transit
5. limiting the use of private motor vehicle transportation
6. reducing the role of national/international brands in city-wide retail
7. progressive (i.e. marginal) property taxation
8. pushing CA on a number of issues, such as non-local tax base for education
The problem is that these policies, unlike the ones dealing with issues like homelessness, would conflict with the desires of the wealth & power classes, and thus cannot be enacted. So you're left with "radical" politics basically being about how the city deals with its poorest, most needy residents, without any fundamental change in the wealth & power relationships that would actually be genuinely radical.