Honestly, the prospect of having parts of my car have to depend on American network reliability is a huge issue for me. I've had friends stuck outside their Zipcars because they can no longer unlock it in the parking lot of a trailhead.
No part of Tesla cars requires the use of mobile networks for basic car operation. It is just the extended functions such as pre-cooling the car remotely, or initiating "Smart Summon" (to have the car drive to you from across the parking lot) that requires mobile network connectivity. If you just want to do typical car stuff like drive somewhere you don't need cellular or Wi-Fi.
Zipcar could have implemented a quick/easy solution to this problem: allow the card to unlock the car offline until it has been returned. Or force the renters to lock it using the keys during the duration of the rental. This just seem to be too common an issue not to have been addressed somehow.
If this is a common enough problem, then maybe the issue is the fact that they offer a marginally more convenient but network-limited option that lulls people into a false sense of security.
It isn't a common enough problem. Over my 1 year of ownership with almost daily driving, I only had to use the card twice. Once when setting up the car for the first time, the second time when I was dealing with valet parking (for obvious reasons).
It is basically a kind of a failsafe solution, just in case your phone dies or something like that.
And mind you, i don't live somewhere where my car gets constant network connection. In fact, the underground garage of my apt building where I park the car has zero network or cell coverage. It all works just fine.
You don't need to have active internet connection to unlock the car with your phone, it just needs bluetooth and an unexpired certificate from Tesla servers, which syncs occasionally in the background. But until that cert expires, it works perfectly fine with no internet. Never had such a situation happen to me before, despite me opening the Tesla mobile app only once in forever.
The phone still worked fine to unlock/drive the car over direct bluetooth to your phone as long as you don't sign out of the app; you just couldn't access the extended functionality or log back in manually (see: activate a new phone) during the outage. I drove all over during the outage without a functional issue.
