google.com/search?q=souther ... 8&oe=utf-8
What has happened is like rape and child abuse, these things always occurred, and at a higher rate, but were swept under the rug, underreporting of rape and child abuse was massive, because to report a rape meant hostility by police (what were you wearing?), your whole sexual history a target on the stand and so on. It wasn't until rape became understood as sexual assault and not "boys being boys" that treatment of victims changed. What child would admit he or she was molested when adults refused to believe and if believed, you became soiled goods. Only after we understood the vileness of predators, that child abuse and incest came out in the open. It wasn't that we became a more perverse society, we became a more transparent society and I suspect the actual incidence declined as visibility increased.
Same with police brutality, cell phone cameras have made it difficult for police to engage in "business as usual" when bystanders can catch you in the act, do you think police were "kinder and gentler" 20 years ago when it was their word against bystanders? Especially black and brown bystanders? The real problem is police unions preventing the dismissal of bad cops, notice most of these shootings and other actions involve police with multiple incidents on their records. Of course, some departments, especially in smaller municipalities, are just "bad to the bone."
Things are better, but they look worse. That is, what was the norm is now considered unacceptable, what would have been page 9 is now page 1. In the long run, pressure to end these abuses will result in more professional and integrated police forces, which in turn will be more effective at fighting crime once those communities that see them as an occupying force can accept them as protectors, and people are more willing to help police rid them of violent predators. However in the short run, the exposure of abuses does generate anger - I mean if you were black, and saw some of these videos, wouldn't you be full of rage and fear? Get shot for having a broken tail light?
The real change will come when policemen and women understand that "bad cops" put them at danger, and instead of covering for them, turn them in and testify against them. Getting rid of the bad apples will keep the rest of the barrel from spoiling in.
As far as the shootings in Dallas, in a country where guns are easy to obtain, crackpots shoot people. Cops, children, coworkers.