Corporate concentration of income and wealth are core features of capitalism. From its earliest cheerleaders like Adam Smith, the drive for corporations to get ever larger and in the doing drive their competitors out of the market was noted and warned against. John Oliver provides a thorough and amusing introduction.
In the US four airlines control over 80% of the seats and in many regional markets the competition veers towards a state of monopoly. There is simply no effective competitive controls on what the airlines can charge and under what conditions.This has lead to persistent high fares and a seemingly endless series of innovations in how many people can be jammed into a plane with as many extra charges tacked on for fewer and fewer amenities.