Every single example of segregation that you have just presented were universally present in southern states in the 60's because of state segregation & 'Jim Crow' laws that compelled private business owners to do so. The "Freedom Rides" events are the prime example of this. The cross country bus companies couldn't have cared less if there were blacks on the same bus as whites, but couldn't allow this to occur in certain states because of the law. The same was true with the segregated bus stations, maintaining multiple facilities was more expensive than intergration, the free market most certianly would have fixed this one in the South if left to it's own devices, because that is exactly what happened everywhere else.
These segregation laws did not exist in the northern states, yet busses, schools ets where de factor segregated there too. Free market didnt help.
More over, we are talking about blacks, a large minority, that in fact, locally had a large
majority. There is an economic incentive there; an incentive that doesnt exist for tiny minorities that do not live as concentrated as blacks did (and to some extend still do).
The 'de facto' segregation of the northern states was a shadow of the reality of the
legally enforced segregation of the south. It's offensive to even compare the two. Sure, there were racists everywhere, and many of them were attracted to positions of power, particularly in the police forces, and thus crap happens. But it wasn't
officially condoned as a matter of state law north of the mason-dixon line. For that matter, the kind of person that would pass judgements upon another human being's character, value or criminal intents based primarily upon a group identity beyond their own control is
still the same kind of person that is attracted to a police career. That much is true everywhere and always. Tribalism cannot be stamped out of the human condition by the simple act of passing a law that prohibits it, and it's the height of arrogance (or irrationality) to believe that it could.