The airlines' discriminatory marketing actions are buffeted by disparate nature of their customer base (a group of strangers who'll typically never meet again after sharing a flight) as travellers don't have enough interest in and means of organizing. Otherwise, if economy class customers boycotted en masse, that airline would suffer more than if a handful of 1st class fliers did. United Airlines' scrambling after the Dr Dao debacle was driven by desire to stem the potential financial loss, not just PR crisis.