I had that happen at a Starbucks drive-up. The guy at the window told me I wasn't allowed to leave via the driveway, either, and I had to pick my bike up and carry it through the flowerbeds out to the parking lot.
Rode my bike to a small local drive-up coffee cart on the other side of the lot, asked if they served cyclists. "Of course!" the barrista said. I ranted about how Starbucks had just treated me, and she gave me a discount... Awww, I love local businesses!
(if drive-ups don't allow bikes they really should post that where it can be clearly seen before the rider gets into the driveway)
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson