Here’s what’s sucking the juice. You obviously didn’t read the text:
Tesla added a remote monitoring system to the vehicles, connecting through AT&Ts GSM-based cellular network. Tesla uses this system to monitor various vehicle metrics including the battery charge levels, as long as the vehicle has the GSM connection activated4 and is within range of AT&Ts network. According to the Tesla service manager, Tesla has used this information on multiple occasions to proactively telephone customers to warn them when their Roadsters battery was dangerously low.
Not only did I read the text, but my long technical background conditioned me to reject ambiguity in critical processes, and NEVER to rely on inferences.
That Tesla "added" something does not clearly report that it is a feature on just the most recent models sold, or they recalled all previously sold cars. See the problem?
Since the article didn't include anything to the contrary, one must assume that ALL cars sold are prone to the same failure, upgraded or not.
In addition, the "added" feature could well, have been powered by a small additional rechargeable battery, which could monitor anything for weeks if not months. Monitoring would not need to be continuous. Unless the main battery voltage drops like a rock off a cliff, brief ( less than one minute) monitoring every 6 or 12 hours may suffice.