Labor unions today: "we'll help you organize and take the legal steps to get fair treatment."
Labor unions in 1912: "take this rifle. If your boss doesn't comply with our demands, shoot him and blow up his mansion."
One of these two approaches gets immediate results.
It's weaker for individual cops. I don't know if it's meaningfully weaker for the capitalists.
To quote Jay Gould: "I Can Hire Half the Working Class To Fight the Other Half"
Hardly a victory for Leftism if NextDoor starts farming out the job of state-sanctioned violence to insecure racist middle-class suburbanites.