Pudding pie in a graham cracker or cookie crust is its own thing, it is not a substitute for real pie. Anyone who doesn't realize this should be shunned. (Its closest counterparts would probably be icebox cake or maybe ice cream cake.)
I'm from Michigan, where the New England influence means that if you just say "pie" most folks will assume you're talking about fruit (probably apple or cherry). But if it turns out you mean pudding pie it won't break anybody's brain.