No, you're wrong. LEO's are not trained to be abusive, but are trained to combat abuse toward them.
As is with human nature, some men and women get a 'power rush' when the adrenaline kicks in that makes them lose a sane thought train. The same holds true when a citizen is confronted by an LEO. Two clashing irrational minds leads to trouble; someone's going to get hurt; and because a cop is trained in self-defense or because he/she's the one with a quick remedy, you can bet who's going to lose, and in the case of the pumped-up cop, results can be fatal.
Humans are not a perfect species, and the public's growing attitude of "nobody's going to tell me what to do" is leading to even more deadly results. Police training facilities do not have the ability to look into someone's heart, mind, and soul to determine their fitness for law enforcement; their fitness, unfortunately, so many times "comes out in the wash".
I guess I owe you an apology for my above remark about being happy; I'm sorry. Your many comments led to my posting that.