Railroads already have police, armored cars are allowed armed guards (as do other high-value shipments, I'm sure), retail stores have security (however neutered they may be).

I don't see why shoplifters are thrown in jail and wage thieves are not. Why do cops gun down shoplifters but won't lift a finger for wage thieves? Why don't cops bust down the doors of polluters? It's the selective enforcement of property rights I have a problem with. The enforcers already side with capital 9 times out of 10.