Depends heavily on how often they did it. A quick estimate suggests that a request like that would cost a few hundred dollars at most: the cost of the food itself, packing it in an insulated box with cold packs (some restaurants can do that themselves, and if not, a shipping service could most likely do that quite cheaply), and about $100 to ship a package weighing a few pounds overnight. Absolutely in the "luxury" category, but a few hundred dollars doesn't seem wildly outlandish for someone making an average tech salary to choose to spend on a meaningful birthday gift for a close friend.
(I say "meaningful" because I'd tend to assume that the reason for the restaurant across the country would involve some kind of shared memory with the place, rather than just a wild whim.)
