Little question

[Lord Sorril]

But then what’s the difference with a mouse , it would be cage open=mouse

That was my original logic when I first kept ball pythons (I did the transfer method as well originally). However, when they sense that food is near they will go into 'feed mode' and strike at warm moving targets. You don't want cage opening/handling associated with triggering 'feed mode'-you want the scent of the food item to trigger it. Some keepers will pre-scent their snake rooms with rodents so they know it is feeding time.

Note: If your snake is very hungry it probably will still take a shot at anything that moves regardless.