It sounds like it currently "cheats" a bit by already having driving rules, maps (including signs), etc. baked in; it'd be akin to a human driver memorizing the California Vehicle Code and a map of San Francisco word-for-word and lane-for-lane.

Presumably Zoox deployments in other cities would work similarly, "cheating" by baking in local driving rules and road maps. A consumer-owned self-driving car would likely be able to do something similar by downloading the local ruleset and maps on the fly, assuming one exists.