Ok a sociology reasoning first. Hopefully we also get to some scientific/definitional discussion as well.
The assertion you make is that lesser aerobic conditioning is required in undeveloped countries than in developed ones because of the inherently higher cardiovascular fitness found in the general populace. (i know i added to that so disagree with me please if necessary)
I agree with that whole heartedly. In fact we can go one step further. I can illustrate with a little story.
Whilst still a competing athlete i coached part time to supplement anything i made from the sport. Over 10 years i attended probably 250 different schools in and around the city i lived in. After retirement from competition i began coaching full time and extended my earlier experience in a more professional manner. It was without a doubt a fact, that rural schools had on average a far higher level of fitness in its students than a city one. I don't think anyone who coaches in schools would disagree and it surely applies to every country in the world.
So yes that part of your assertion is a great one and totally valid by my view.
The next aspect confuses me and possibly part of that confusion is definitional.
Developed to me means all of the first world countries. US, UK, Europe, Australia, New Zealand, China etc.
Undeveloped would third world countries like Kenya.
So do you mean something different by your usage of these two terms? Or do you have it backwards?
The final problem is that you group New Zealand in a different category to The US, UK etc. I'm wondering at the rationale of this. Can you explain? Since it seems to be your explanation of why Lydiard might have placed so much emphasis on this part of the training, as opposed to the other reasonings that Lydiard himself has offered, i think its important to follow up on.
cheers
gypsy