Clearly they do get away with it, since they keep running these 'fake' / misleading promotions. They will continue until someone takes legal action against them. Knowing QR they will probably still continue even if they lost a court case!
I haven't checked for the current promo, but I booked a ticket in January(or February?) that the VISAWKD code reduced by ~35%. After entring the code, there were a number of very limited business promo fares available that didn't appear without the code.
Finding that city pairs between and the dates on which the code works is however tedious.