Do codeshare & alliances conflict with competition?
Alliances are the airline industry's way of corporate mergers. Since national airlines are still regarded as a symbol of national pride and often are part-owned by the respective governments, eradicating the proud name from the industry would be too hard to swallow. Therefore, alliances are formed in which tariffs and schedules are harmonized. The effect for you, the customer, is the effective removal of competition, resulting in monopoly pricing on routes which are served exclusively by carriers of the same alliance.

This can be compared to the car industry: Chevrolet is not competing with Pontiac or Cadillac, regardless of what the advertisements say. You might think that the wider choice of brands is a benefit, but in the end the benefits are mainly on the side of the industry.