Not sure - if I was designing it, feels like it would be a good way of getting the right build to the right car so that all the HW versions of each module are in line.
I'd imagine that the update includes all the possible hardware, and the update script actually decides which components to use. Like apt on Debian or yum on RHEL.
It appears that the Tesla is running a full Ubuntu Linux distro. And here's a small quip to entice passers-by to read more:
> With names ranging from “INDIFFERENT” to “SUICIDE_BOMBER”, there is a list of escalation strategies in the updater binary, which appear to be strategies for retries of downloads and user prompts on the UI.