This is true but there is enormous pressure for these businesses to directionally encourage review scores to trend north. Higher reviewed locations and business

This is true but there is enormous pressure for these businesses to directionally encourage review scores to trend north. Higher reviewed locations and businesses always garner far higher engagement, and this directly impacts top line. As you point out, there is some ephemeral point at which users might begin distrusting the site en masse, but this inflection point is always easy to ignore as "a problem for another day far in the future." In the mean time, tiny but substantial changes occur all the time which nudge that score higher and higher. In my experience, that macro trust issue is rarely discussed, even though, at some undefined point in the future, it could pose a serious existential threat.