These (apparent) e-mails between an owner with the dead battery issue and Tesla seem to indicate that there is a a 'built-in notification system' for this, but it wasn't added for the first 500 cars : http://jalopnik.com/5887504/tesla-emails-gallery/gallery/1
A problem like this really needs advance warning, not just a notification when the problem is about to develop, since the owner may not be in a position to get the car plugged in if they don't know it could occur beforehand.
Which is why there are warnings in the manuals. Which puts it on par with changing the oil in a regular car, if less culturally-obvious. Reading a manual for something you spent $100k on seems a reasonable prerequisite, especially if you have any interest in keeping it running.
