system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Is their an in-universe explanation as to why B1 battle droids have personalities?

Maybe personality isn't the right word, but many of the battle droids we see act in sentient fashion when it doesn't make sense, i.e. when they have the drop on jedi they have been instructed to kill, they demand surrender rather than just shooting the jedi in the back. Out of universe it is clearly just a joke or a plot crutch to keep characters alive, but what about in-universe?
gpt
Droids tend to develop personalities if they don't recieve regular memory wipes. Since B1s were designed with quantity over quality in mind the Seperatists likely didn't bother with frequent memory wipes to save costs.