I actually understand what you're talking about, Twila. And I agree with you to an extent. But several things need to be separated.
Military vs. police - very different scenarios.
Police vs. police - Maybe it's different in Canada, I hope it is, but while it's true, as they say, that "most cops are honest people doing an incredibly dangerous job," that should be "many cops" and the job ain't all that dangerous.
Just as many cops are honest, idealistic young men and women, many really are thugs. Many are people of mediocre intelligence, inferior education, and bad attitudes who get their rocks off pushing people around and having "authority." This attitude is focused and reinforced by their training, which is increasingly militaristic (not military), and emphasizes how the people they encounter are enemies to be dominated, not citizens to be served. They also have complete contempt for Constitutional freedoms, and work hard to find ways around them or through them.
Many, probably most, bad cops weren't turned bad by their experiences. They started out pretty bad, and were turned really bad by their training.