Unsure on the prison thing, it's not really explained in setting if [i]anyone[/i] other than the NCR way out west bothers with prisons. I feel like most just feel it's a lot easier and uses less resources to just put a bullet in someone or declare them persona non grata. There's probably ways of doing those things and getting away with it, just a matter of knowing what happened. Entirely likely that after the BoS soldier was killed and Warrick escaped, they simply couldn't be assed to pursue beyond their immediate territories.

After all, who has time to care about anything other than their land and what happens inside it? lol