> They can't get an edge over each other and their models don't even differ in the ways people naturally differ, of having different opinions about things.

Of course - the models are not individuals with their own opinions - they are averages of human opinion, and given the scale of the training sets, the data they are averaging over is mostly in common between models (at least for the common core before company A vs B adds a dab of some uniquely sourced specialized data to the mix).