Originally Posted by orbitmic

On the general point, I would say that you have then been very lucky (or perhaps didn't need to cancel that many tickets so may have not realised some may have had similar restrictions if you didn't need to cancel?) I would say that non-refundable is in fact a very common restriction on discounted fares (though some airlines surpensed the rules on refundability specifically during covid).

cws gave the specific rules on this, but a more general answer to your point is that whilst many fares are non-refundable, historically, non changeable are rarer, so typically easier to change than cancel. Having said that, non changeable have become more and more common of late (not least with QR but also with US airlines!) with the increase of light/basic fares which are often non-changeable. Hopefully, the change will resolve things this time round anyway!