> Sears: had Allstate for insurance and Discover Card for credit. Unlike most "branded" credit-cards, Sears did its own underwriting for the Discover Card i.e. they owned the Greentrust bank

This was a fairly common thing to do, as you point out, for department stores. As far as I'm aware, Target was the last holdout department store owning its own bank, Retailers (then Target) National Bank, through which it issued the RedCard and RedCard Visa, and sold to TDBank. Macy's had Department Stores National Bank, which it sold to Citi, and so on.