I recall seeing a post a while back detailing a dinner conversation with a EZY accountant on this very subject.
This above 'post' as source, TheBeak is quite correct in his analysis of the managerial perception of the pilot work force. Beak is not suggesting that it is desirable, or even accurate, but it does explain why PTF is ubiquotous. Revenue generated from these 'Ruperts' in their 'Gold Bars' is highly attractive and supports the management bonus. Fabulous!!