Maybe the siege men could... use the open gate?

[DrSunshyn]

No, instead, they're pre-programmed to still use the ladders. So must be manually commanded (hard to do to each unit in a siege, and stupid) and when you die, they go back to ladders & losing. Just not good programming here

 

[Tasak]

If you are not talking about Bannerlord (because you have been active in its section), that is why it is better to play multi-player Warband sieges when others are smart enough to use some advanced strategies to win. Single-player sieges are very simple, just climbing ladders and fighting until the battle is over. Opening gates can be done only in multi-player.