It depends on the local standards of what is luxury and what is a necessity. In America Rolls Royce is a luxury but shoes are necessity. In some Asian countries people still go barefoot.
This gets to the root of the problem.
First, a Rolls Royce is a luxury no matter which country you are in. Second, shoes are not a necessity except in certain climes in America.
A model? Hey, I like models...
Air. Is Air a commodity or a luxury or an intrinsic right?
Bear with me. I ask this in seriousness. I wish to demonstrate the nature of what we think of as "commodity".