For example, with T-mobile, I can register my credit card, and if I use that credit card at any of the participating outlets, I can earn cashback. Similarly, if I register a non-Bilt credit card with Bilt, then I can earn Bilt points on ‘eligible spend’. How are they able to access my credit card transactions? and are they getting access to only the participating outlets, or all of my transactions? and what do they gain by doing these schemes other than increasing their brand value?
I don’t know how it works in this case but if a commercial for-profit service is gratis, the general rule of thumb is that you are not the customer but the product.