Also, for a human there is cognitive load in moving around. If you are safe where you are now and nothing significant changes, it's mentally easier to stay stil

Also, for a human there is cognitive load in moving around. If you are safe where you are now and nothing significant changes, it's mentally easier to stay still instead of re-evaluating everything constantly. And this frees your brain to better plan your next move, so it's advantageous. For an AI, CPU power isn't as scarce. And even with a computer playing a video game (not the real world), your joystick hand gets tired.