".....then surely carrying grain to and from a mill was no problem for him..."

It is very difficult to not think as 21st C people with our vast distribution networks for food and other commodities. Prior to the last couple of hundred years overland transportation of bulk goods was very difficult and food, unless it could walk, was processed locally. Every farm would have had its own threshing floor and the grain taken, probably by horse, to the local mill of which there were many thousands spread over the country. To the people then the idea of centralised processing would have been quite alien.

In the Neolithic period the mindset was probably similar although villages and towns as we know them didn't exist. Food for everyday living would have been prepared in your own backyard. Trade certainly existed over huge distances but seems mostly to involve high "value" goods which were easily carried.

Scene One.
(Late Neolithic)
Mrs. UG "You know all that work we do to thresh and winnow the corn round the back of the tent, well, I've heard that there's a thing what will do it up on the plain."

Mr. UG "Will it grind it as well?"

"Um...No"

"So we have a two day walk carrying girt great bundles of corn, bring all the grain back and for what? And what about all the food we would need as well and there's the kids to think about and you know my arthritis is giving me gyp. I'm not so young anymore I'm nearly 25 y'know"

"I've heard that when the big hot thing in the sky hits the ground at certain times of year they have HUGE parties up there. Fancy going?"

"Now you're talking! We can leave the kids with your mother."

"Rave on!"

END

Jim.