I'm not sure what type of software updates we're talking about but BMW allows idrive updates (nav/media) via the USB port. They provide the updates for free on their site.
I drive a Hyundai that has a navigation system. I purchased it in 2010. I have to dish out $250 or something at the dealer to get updated maps. The nav system's update process is password-locked so I can't just do it myself.
We're talking about pretty major things like new features for Autopilot, and performance enhancement from better battery/motor management.