I imagine that the Batkids go out for food every once in a while.
So there they are all sitting at the restaurant, when dick goes to pay and accidentally uses one of Bruce's cards.
They get back to the cave to bruce freaking out, everyone is like "IDENTITY BREACH AHHHHH" y'know.
And the next day a paper comes out, "Bats steal Brucies Credit Card!"
From then on they use Bruce's cards for snacks in the field and gotham just accepts that
1. Bruce funds the Bats
2. They take it from him
3. Bruce and Batman dated and Batman stole his credit cards and gave them to his kids.
















