I once had to be towed because the key stopped working. This was a Smart Roadster (still the greatest car I ever had, nonewithstanding). A battery change didn’t work and the mechanics sent me 100km to get the spare key.
So there are definitely circumstances where the phi’s always artifact alone just isn’t enough to start the car, only to get in.
Don't know how universal it is, but my keyless car has separate failsafe for entry and start. To get into the car, you can slide the physical key out. To start the car, you use the fob to push the start button which I understand to use a passive circuit similar to credit card tap.
So there are definitely circumstances where the phi’s always artifact alone just isn’t enough to start the car, only to get in.