I don’t know why anyone would ever take their key out.. it’s connected to the top of the fob. Strange, but yeah, that could happen if someone dissected their key fob lol.
I will tell you that I know someone who started their car remotely, got in with the fob and pushed the button, then ran back inside and set their key down. Drove to work, turned the car off, went to go to lunch and realized the key was at home. Had to wait to drive until wife could bring it later.
That situation can not happen with a key that must be in the ignition!!