My sense is that these transfer promotions are driven by the airlines and hotel chains, not by the credit card issuer. For example, I see both BA and VS offering similar promotions for American Express (USA and UK), and Diners Club (Canada and USA).
No doubt the card issuer has input into the timing and other details, but I believe it is the airline which bears the cost.
except rbc then. maybe they pay, which is why it's so regular