Graeber's argument in the book is that businesses are actually run like the government, ie are bureaucratic institutions (that pretend to be "markets"). He has an interesting story about how they were modelled on the post office originally, when large businesses arose in the late nineteenth century.
In Europe, companies were originally gifts of a private trading monopoly made by a monarch. The Post Office model happened a lot later.
There should be more of a distinction between "efficient" used to mean "gets things done effectively and invents new and clever ways to get things done while saving everyone time and money", and the capitalist meaning of "accumulates profits by screwing everyone except senior management and perhaps the stockholders."
It's perfectly possible for the latter kind of "efficient" company to be very inefficient in the first sense.
In fact if you have a market with a very limited number of established large players, it's pretty much the default.
