I meant public in the sense of publicly owned by the collective people, not publicly traded vs privately traded.

All the decisions of the companies are made by private individuals. Sure they're legally obligated to turn a profit for shareholders, but that doesn't mean they're in any way beholden to the interests of the public. In fact this legally demanded profit motive for publicly-traded companies often causes behavior that is in direct opposition to humanity's well-being, and that's obvious even with just a cursory glance at the news.