And when "they" say "Fruit and Veg", "they" mostly mean veg, and "they" don't mean potatoes - "they" mean greens and other above-ground veg. Ten times a day? Fuck that. We're hunter-gatherers - when in our history (even post-farming era) have we been able to hunt/gather/farm plants on that scale?
*Ahem*
Studies of the few remaining hunter-gatherer peoples, like the San, suggest that the most of their diet is plant based, i.e. they are gatherer-hunters. And that a _very_ great deal of time* is given over to foraging for edible plants. The meat bit is a, relatively, infrequent bonus. So the eat _lots_ of plants advice tallies with our, likely, pre-farming way of life.
Slightly OT. I have come across articles which argue that moving to farming was, from a dietary point of view, a complete fuck up. People went from a varied diet of whatever the hell green stuff they could find with a bit of meat thrown in now and again to diets based almost totally on cereals.
What farming allowed was increased population density (albeit unhealthier individuals) and all those things that make the modern world possible like reading, writing, political systems, taxes and bureaucracy. Actually putting it that way farming was a bloody stupid idea wasn't it?
*And guess who does all that tedious gathering bit while the blokes sod off to the footy^w^w^whunting?