The phone and keycard are keys. If you lose them, you lose access to the car.
Also, I usually only use my car keys for one purpose. I'm using my phone all the time, for a variety of purposes. I've had my phone stolen from me when I was using it for one of those purposes, and meanwhile, my car keys were still in my pocket.
The phone and keycard are keys. If you lose them, you lose access to the car.