It's I'd venture a symptom of a culture dominated by capitalism and corporatism, such that the former two things become so dominate that their presence is invisible. Malls and Facebook pages become "public spaces" in the minds of citizens even though they are spaces, public regulation notwithstanding, controlled by the rich and existing in the main to profit them.

Public/private can refer to government vs commercial, or it can refer to “out in the open for all to see” vs “the privacy of your own home.” “Public space” is a common phrase that uses the latter definition. https://en.wikipedia.org/wiki/Public_space

The idea that the mainstream media is somehow overwhelmingly progressive is something conservatives like to parrot, but I've never found it to have any basis in truth. The "leftist" big media outlets are really centrist, at best.

I'm going to have to ask for a citation for that. Unless you are suggesting that supporting the interests of the rich elite is an essentially conservative position (a claim which both the rich elite and conservatives would deny).

If you look at the politics of all the people (executives and rank-and-file) working in the institutions of media, entertainment, and academia, you'll find that a significant majority are left of center given the generally accepted notions of left and right as they are used in contemporary American politics.

Where is the evidence of this? I know of no surveying so broad as to include the executives and 'rank-and-file' in media and entertainment.

Even if your claim is supported, we have 2 problems. The first is basically the "vegan waiters at steak restaurants" retort, which is to suggest that below the top executive level of the hierarchy employees have increasingly little power over their organisation, such that those at the bottom are like vegan waiters at steak restaurants who have no power to change the menu despite their politics.

The 2nd problem is basically that "left of center" != "progressive". The majority of the ostensibly left-leaning medial is still broadly pro things that progressives are against. Some examples would include single-payer healthcare, animal rights, public higher education, the Green New Deal, and anti-imperialism.

All of the major media outlets (which is what I am talking about, not academia or entertainment) are owned by big backers of the Republican party. It's publicly available information, look it up yourself.

It's a good term though...