CAUTION: Always carry your key card with you in your purse or wallet to use as a backup in case your authenticated phone has a dead battery, or is lost or stolen.
Again, sure maybe people will NOT do this, but you cannot blame Tesla for this. Services fail all the time. The phone as a key is just a convenience. This same silly FUD went around earlier this year as well. Nobody got locked out of their car by a failure of Tesla. They locked themselves out of their own cars.
It's also posted in the car when the phone key is added. In my case, the handover agent specifically told me to keep my key card with me. It's not really a secret, nor is Tesla saying you should only use your phone as a key and nothing else. Tesla's marketing is that you can use your phone as your key - and they're right, and it's also very convenient. It's not the same thing to say that users should only rely on their phones. They can't anyway, since the car will require the key card when adding a phone.
Of course, if you read that literally, none of those things ("phone has a dead battery, or is lost or stolen") happened, and Tesla's screwup still caused a problem.
(Note, both my wife and I own Model 3's and I own $TSLA, so I'm no hater... I do carry a card key in my wallet, but I don't carry my wallet 100% of the time that I need to get into my car.)
From the Model 3 manual:
CAUTION: Always carry your key card with you in your purse or wallet to use as a backup in case your authenticated phone has a dead battery, or is lost or stolen.
Again, sure maybe people will NOT do this, but you cannot blame Tesla for this. Services fail all the time. The phone as a key is just a convenience. This same silly FUD went around earlier this year as well. Nobody got locked out of their car by a failure of Tesla. They locked themselves out of their own cars.