easyJet carry quite a number of TUI customers from Luton.
True - but EZY's LTN operation was a similar size when TUI had 3 aircraft based a few Summers back. Another factor is that it made sense to keep a 757 based at LTN on rotation for hangar A checks. Obviously, now that type has left the fleet, the company feel they can make better use of 737 aircraft elsewhere and virtually all the once LTN based pilots relocated to other bases during the peak of Covid.