They do. It's called finding another job.
Eric: It isn't if you can't go and work somewhere else.
— J. B. Priestley
Not everyone is in a position to find another job. And what do you do if the best place you can work is still rubbish? What if you're an ISP tech?
Okay, sarcasm aside; I've worked for many different tech companies and good managers are exceptionally rare and there is no pressure from the top to change that, and pressure from the bottom doesn't work. There is, however, a lot of pressure to not fire or demote managers as it looks bad for the management above them.