All the bigger software vendors make updates available to all users; many provide them free for download. Smaller vendors often do, too. And Google does, but the carriers sabotage their efforts. Even Samsung admitted after a while that one of their earlier update delays was due not to the claimed hardware testing, but to their own user interface overlay crapware.

Even your example of the car industry belies your assertion: every one of them provides detailed specifications of maintenance schedules and actions, and, if there are safety concerns, even where not directly attributable to design errors, they have government-mandated recalls to fix the problems, and often recall without government interference.

NONE of this is regularly available from carriers. My wife's phone, a Verizon Galaxy S Fascinate, is still at 2.3.4, which was already out of date in April 2010 when she bought it.

She'll be getting a real phone this coming April (that she'll be able to use during our occasional trips to Europe -- hooray!), with service from a less arrogant carrier. Mandatory data plan, indeed!