This is because of government intervention (it's illegal for Christ's sake).
> Neither has wheat, sugar, electricity production, coal, iron, or copper.
Wheat has been regulated forever.
Sugar--are you not aware of the corn lobby?
Electricity production: this is pretty well monopolized regionally.
Coal: not yet.
Iron: USS wasn't a good enough a monopoly for you?
> A natural monopoly only exists in the face of high barriers to entry. Those barriers may be natural, or they may be political, but either way they must be high. Some may be high enough to only have a few competitors, but compete they must do. Collusion is mathematically and empirically unstable. In fact, the economic criteria for cartel success is a) how much profits increase, and b) how long they last. There would be no need for `b` as a success criteria if they were stable.
What makes you think that a large company will not create high barriers to entry in their field? When a company reaches a size where they can lobby the government successfully the field ceases to be an even playing field.