Then why don't employers, the ones with essentially all the power here, tend to choose actions that go against the interests of the working class? Simple: regardless of what you think "should" happen, a study of history tells us what actually tends to happen in reality, and that tendency is towards class war between the ruling and exploited classes.

Anyways, in what way is "ownership" not rent-extracting in general? If you own shares of a stock and you get paid a dividend, that is rent plain and simple. All the arguments you can make against that being the case -- eg that you deserve a premium for parking your capital in a risky asset -- apply to advertising conglomerates and even literally renting out land too, so either they're all renting or none are.