If you visit TUI's websites (not just UK but other European countries as well), you will see many flights available either only on package holidays (ie not available as flight only) or being quoted at vastly inflated flight-only prices. I can think of other package-holiday-centric airlines in Europe which do this as well. Jet2 are definitely not the only ones doing this.
If you want a particular flight, you may need to wait until a fortnight before travel date when a firm has a better idea of how many seats will not be sold for package holidays and starts releasing the remainder for flight-only sale at realistic prices
The relationship between airline and paying passenger is a business relationship... and the airline aims to maximise profit.
Last edited by davidjohnson6; 15th Feb 2023 at 11:52.