Not much. I have civilian neighbors who are just as bad though. American police have never been much different than they are today. Wyatt Earp was (eventually) a federal Marshal who rode people down and blew them away without trial. Sheriffs have been harassing black people and immigrants since the end of Reconstruction. Police of the western territories in the 19th Century were notoriously brutal. Now there are so many federal police that no one should even think of being disloyal. Today border patrol cops consider our southern frontier a warzone, so rarely take any chances. A barely-literate person who was forced off of welfare to become a TSA guard will look at your wife naked on an x-ray, harass you, and grope your kids at an airport checkpoint. During the American Revolution, American guards would strip-search male travelers at checkpoints. How do you think Benedict Arnold's plans to betray West Point fell into our hands? Go even further back and towns were hanging people for witchcraft. The scale and technology are all that have changed over the years.