If soemone offered £ 20 off
Air Canada had that idea a decade or so ago, Charged an all-inclusive price and then you could choose to deduct those bits you didn't want; checked baggage; seat selection; miles; etc.
It didn't last for long.
Does anyone here know why they abandoned the idea (which I liked immensely)? I suspect that it was because their growing domestic competitor applied the opposite model. Low initial price plus add-ons.