LORELAI: So, who taught you about all this business stuff? Your dad?
LUKE: Please. My dad didn’t even have a checking account until I finally got taller then he was. He bought this land with cash from working construction, built this place himself. Didn’t have a bookkeeper, an accountant, or anything.
LORELAI: Wow, so you had no one showing you the ropes.
LUKE: Nope, I figured I had to just dive in on my own, fail if that’s my destiny, and forget what the experts say.
Note that this back story changes slightly later on.
Is it really possible that Luke learned nothing at all from his father before he died? William Danes ran a hardware store, he must have known something about business, and Luke worked alongside him when he wasn’t at school. Surely he picked up a few hints at the very least, especially as William would have been expecting him to take over the store one day (which, in a sense, he did).