They actually do an impressive amount that they don't have to (my dad is a Tesla fan/early adopter and has a Roadster, Model S and probably will get a Model X eventually).
When he took the Model S in they added that metal plate to the bottom (from that one crash that got a lot of press), swapped out all the door handles for new ones because people online complained that in rain sometimes the old ones wouldn't retreat into the car and changed a few other things I'm forgetting (at no cost).
I can't really think of another car company that proactively adds a bunch of stuff to the car for free as a part of routine maintenance. Of course this is in addition to all of the over the air software updates too.
In all fairness, most of that is warranty repairs. The initial door handles, for example, had reliability problems worse than your dad saw, which meant all of them ended up being replaced. (My car ended up having one replaced twice, because apparently the new version also has a problem, albeit more minor.)
Adding backup lines to the backup display, on the other hand, to 2 year old cars, that was unusual. It was purely a software upgrade.
When he took the Model S in they added that metal plate to the bottom (from that one crash that got a lot of press), swapped out all the door handles for new ones because people online complained that in rain sometimes the old ones wouldn't retreat into the car and changed a few other things I'm forgetting (at no cost).
I can't really think of another car company that proactively adds a bunch of stuff to the car for free as a part of routine maintenance. Of course this is in addition to all of the over the air software updates too.