I'm guessing the distribution of reviews was bimodel. Ideally, people should use a 5-star system in a way that it provides a normal distribution. Most content should fall between 2 or 3 stars.
But it doesn't actually work that way, 4 star uber drivers get kicked off the platform, 2 star Amazon products suck, 2-3 star movies suck. 4-star movies are okay.
As such, I think we can conclude that people don't actually know how to use a star rating system and we should just get rid of it.
I wonder if letter grades would be the way to go in relevant countries. Most people have internalized what a “C” means pretty well, even taking grade inflation in to account. Hell, that’s the whole reason 10 star rating systems are bad, as people treat 7 like it should be average and 5 is a failure.