I know quite a few food delivery drivers and most work for multiple companies (even if several are subsidiaries of the same parent company). This is by design so labor can be denied the benefits required of a full time job. It’s not only inefficient, it’s exploitive.

Which history has shown that monopolies (government-run or otherwise) tend to get less efficient because of the lack of competition.

Companies that compete do get more efficient, but only at making money. They do not get more efficient at providing service to customers or supporting their laborers. They usually get worse in fact. That is why we have regulations.