peaceful 75-year-old protester unconscious on the ground with blood coming out of his ears, page-92

"They now have the equipment and appearance of someone engaging in heavy military combat."

Because America is such a deeply divided country between rich and poor. A tiny handful of billionaires (Trump is one) control more wealth than the bottom 50% percent of the population.
The police enforce inequality, as inequality grows the "enforcement power" of the police must grow. They need a lot of firepower to suppress millions of poor people.