Keter you are mixing two different situations up here and trying to charge no-show fees for a cancellation. Cancellation fees appear to be USD 800/400 depending upon when the cancellation is made. No-show fees are USD 2000.

If you are so rudely inconsiderate and do not cancel beforehand then you are a expensive no-show the you must expect to pay some of the extra costs you inflict on QR. If you want more flexibility and lower fees then you should have purchased a higher priced ticket class with more flexibility. The fees are clearly displayed by the booking engine when making a booking so you could not be ignorant of them.

Unlike most other airlines QR do not deliberately oversell flights and are making efforts to try to reduce the number of no-shows in order to give passenger the best possible service.