I keep hearing about the same managers over and over again. Everyone talks about how mean they are. They have a job to do. They are responsible in making sure you do your job. If you don't do your job, then managers pay for it also. If you want them off your back, do your job. You're not getting paid to play Candy Crush or talk to friends and family on the phone. You're getting paid to do your job.
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Get to your department, get off your phone, and do your job!
Management absolutely do their jobs or they will eventually lose them; at times bad managers can find enough scapegoats to make a long run of the job, sometimes a lifetime award for scapegoat slaughter is due. Sometimes managers end up harassing the 'hard workers' because they can't differentiate truth and misdirection by co-workers and department heads alike, their purpose is to cause mischief and/or disciplinary action sometimes which results in termination, all for the drama. I've found this to be true at non-union and union shops alike, but I find union processes to at least give a determined worker a chance to respond in the majority of cases.
All in all, I see where you are coming from, but you are generalizing one group while giving props to another group.