oba510
There *is* an actual stairway here, it's just in really horrible condition.  It's entirely on public property, along with the rest of the alley. 

https://wiki.openstreetmap.org/wiki/Key:trail_visibility and/or https://wiki.openstreetmap.org/wiki/Key:smoothness might be useful here?

You can barely see the steps here, next to the retaining wall and half-covered in ivy: https://www.bing.com/maps?osid=2148b2c3-342c-433b-a208-f48939dbf2a2&cp=37.884174~-122.265797&lvl=19.0&v=2&sV=2&form=S00027&style=x