"I just had a conversation about this with a retired K9 police officer.
In their opinion, there are certain breeds that are just more unpredictable regardless of upbringing or training. Pitts are one of those. It's not that they're bad dogs but due to their high prey drive or high protection drive, they tend to be just...unpredictable. In this person's professional experience, they hated pitts and more problems with them in general.
I always believed that it came down to training and not the breed; however, this person completely disagreed (again, this is a person that I would consider an expert being a K9 officer as well as military K9 trainer...and a lover of dogs!)"