I've managed to get top spec'd models at Apple Stores in Australia too. I think they carry limited quantities of higher configurations for each model. They're aware some people need more storage.
It makes sense for them if someone walks in wanting a particular configuration that they can offer them something very close and send them away with a sale, rather than telling them they have to order online and wait a week.
Ok thank you, I've seen that they are also available for order online and pick up in store, my only issue with that is being able to order one and then pick up on a specific date, because the nearest Apple Store is Birmingham for me, it's a few miles away from where I live, and I go Birmingham shopping a few times a year.
It would be great to just be able to walk in the store and buy one there and then, I think I'm going to wait until later this year anyway, mainly due to spec updates like Kaby Lake and there have been rumour of price drops also. Plus I'm still deciding between the 13" and the 15"