The term 'LOW COST AIRLINE' is not and never has been a reference to the fares which customers pay. The term quite literally means that the inherent cost of operating the business is kept below those of traditional legacy carriers. This is achieved via the way the business is structured. What the customer actually experiences is a 'NO-FRILLS CARRIER' ... an airline which compartmentalises every aspect of the flying experience and charges by component of the itinerary ... add-on fees for all 'frills'. Note that whilst fares offered by these carriers often are attractively priced, they don't have to be. There is no implied promise that all customers will pay a low fare. These carriers are businesses which exist to maximise profits, and they do this by deploying yield-management software to maximise revenues like every other airline.
The paragraph quoted above is extracted from Post 261 on this thread in which I explained the true meaning of the term: 'Low Cost Airline'.
Why do people doggedly refuse to acknowledge the truth of this? 'Low Cost Airline' is all about the balance sheet. It is not a guarantee of low fares.