Jail/prison is a scary place for many. Regardless of it being scary or not, nobody other than the extreme homeless want to go into prison. There is nothing worse than losing your freedom and being forcibly confined to a single area with lots of other unsavory types of individuals. Regardless of this fear, many people will still commit crimes. It is when they get caught that they regret their actions, though not everyone.
Due to this dislike for prisons, some criminals adopt a never taken alive approach. It means they will do all they can to evade the police, and will even resort to using illegal deadly force to avoid being arrested.