I hear you and this is a problem that I currently face as well! We actually source offer data from all the major credit cards and one of the features we are going to implement is to show you offer data next to your optimal card (once we make improvements to our optimal card decision engine)

The idea is to later incorporate the promo and give you the ultimate best card, something we still need to figure out and perfect but as of now we can show you the best card for groceries and offers on the merchant selected