Shareholders can do more than just fire the management team, they can set meaningful objectives and tie management compensation to reaching them.
Hell, this entire post exists because some Google employees care more about their values than about making as much money as possible.
I can assure you if google employees revolt on a number of projects and that drops the stock price in half over the course of 3 weeks PEOPLE WILL CARE... Even the ones that today you say don't care.
There are an awful lot of people in this very comment thread who would claim to be counterexamples to this. Are you going to say they're all lying or deluded about their own motivations?
What an absurdly preposterous thing to say. Money is a motivator and a large one for many, many people, but it's ridiculous to call it the sole motivator for everyone.