Someone who claimed to know about these things told me that the powers that be consider people changing wheels at the roadside are in a very dangerous situation and so these powers are doing everything to stop it happening. Safer to call a recovery truck.
Another person who also claimed to know about these things told me that it's simply to lose weight and therefore produce higher mpg figures plus claiming greater luggage space(where the spare wheel would have been).
Nick
A lot of that has a ring of truth about it in the way they fiddle the figures, most manufacturers of course not just MMC.