Efficiences generate monopolies, not competition:
Every cheapening of the means of communication, every new facility for the free interchange of ideas between distant places alters the action of the forces which tend to localize industries. Speaking generally we must say that a lowering of tariffs, or of freights for the transport of goods, tends to make each locality buy more largely from a distance what it requires; and thus tends to concentrate particular industries in special localities.
-- Alfred Marshall, Principles of Economics, (1890) Book IV, Chapter X, section 4
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