It's not as bad.

Modern keyfobs actually detect motion and if they are motionless for a while, they stop transmitting the signal to both save battery and prevent such attacks.

For old keyfobs, you can get a battery sleeve with integrated motion sensor which does the same (cuts power when fob is not in motion for a while).

Alternatively, some cars let you disable the feature and just use the keyfob as you would use an older one - then you habe to push the button anytime you want to unlock the car.