Does such a product currently exist, or is it theoretically possible to create, a singular plastic or virtual credit card that does the following:
- Determines the merchant category of the transaction
- Integrates with banks and credit providers to check current cash back reward categories and current balances
- Can dynamically, at transaction-time, charge another credit card based on those calculations
For example, it would be really useful to have a "one-size-fits-all" credit card in your wallet. Swiping it at a gas station may automatically charge my Discover card during a seasonal 5% cash back period on fuel, or select my American Express at grocery stores, or my HSA card at the doctor's office, or my Visa for a large transaction I might not be able to pay off because it has a lower interest rate.
I couldn't find something like this--so far, the closest I have seen is a physical credit card with an e-ink display that allows cycling between other credit cards whose numbers are programmed in through an app. I am wondering if this is the only way, because maybe a credit card has to actually represent an account and cannot simply process transactions on behalf of another arbitrary card.