My point was and as previously suggested here, if more people complained and if, for example BA, found themselves frequently shelling out various two hundred quid tokens per flight - just to keep the punters quiet - then hopefully, someone at Waterside will eventually realise, even although it's a trifle costlier, it's better to keep most of the people happy, most of the time.
Is that really what they are doing? They are giving you a voucher which can only be used on another BA flight encouraging you to do exactly that (No more "I'll never fly them again"). I don't think they are valid for ticket purchase either, but you might even pay a higher price just so you can 'use' your voucher. Crafty.
The vast majority of people do not buy on board and on BA that would likely be for booze, death sticks, gadgets, perfume, and other stuff. So giving you a voucher they are stimulating purchases. Perhaps you would spend even more than the voucher amount. Do they actually lose, not with every pax.
I don't see this as being completely altruistic on their part, more manipulative. I'd rather have £20 cash than £100 in vouchers.