It’s just a confusion between two different valid definitions of the word public, not some indication of the state of the culture.
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
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.