What makes you think the police have become more “respectable”? Shows like “COPS” and “JAIL” do not necessarily reflect reality no matter how they bill themselves. They’re performing on camera, so of bloody course they’re going to be on their best behavior.
Granted, some of the more egregious abuses like jailhouse beatings have become less common (although they still occur) and some jail conditions have been marginally improved, but this has mostly come about because it was forced by such entities as the much-maligned ACLU, not because the police had any desire to improve treatment.
Actually, within the last 20-30 years the police have gained a whole slew of new weapons, communications equipment, manpower, and many new laws designed to give them more power. Ostensibly, this was to help them do their job better, but since police work appeals to those (if not only those) with a bully instinct, all that was really accomplished was to give them additional opportunities to be hard-nosed, legalistic bullies. Meanwhile most public oversight was removed.
In a fairly eventful life, I’ve had some small experience with jails (just jail, not prison, and all short and fairly minor.) First was nearly 30 years ago, last was about 3 years ago. I can attest that the early experience was far less unpleasant, and the officers more personable and flexible than the jack-booted psuedo-military thugs one sees today.