As many who have lived on a farm and planted and maintained pasture know, a proper grazing system includes very little actual grass. For our sheep,we have a field planted to grasses hardy in Texas, as well as soybeans, alfalfa, clover, milo, and many other things that are grain plants. In the winter, or the summer, if the pasture gets parched enough, we feed supplemental alfalfa (grain), and, during lambing, we supplement with oats and even corn. Pastured "grass fed" cows, properly managed, are fed in much the same way. But how much energy goes into all this? Very little. We planted and maintain our own pasture, so we passed over it once with the tractor, and, occasionally, very rarely, we need to mow a bit, or throw down some seed in a bare patch, which we do by hand. The hay is a bit more intensive, as another farmer planted and baled it for us with his equipment.
Compare that to the constant operation of a feed lot, the manure piles so high the cows lay on them for some comfort (my sheep lay on a thick carpet of relatively manure and mud-free grass, as do properly pastured cows). Manure lagoons that span acres, cows being fed such things as chicken scraps, other cows, until that was outlawed, and even gummy bears. Yes! Google it! Gummy bears! Including a rich cocktail of Heaven only knows what drugs and horomones, and going to slaughter so sick they can barely stand.
My husband and I have had several talks with neighbors who raise cows, and given serious financial consideration to adding cows to our operation, and have found that cows actually require slightly less management than the sheep do on an open pasture, a simple change in our pasture grass cocktail to reduce forbs, and we are there, so the management practices are not that different.
A grass fed cow is not a cow that has been turned loose on the native terrain of their local area. It is a cow that has lived in a lovely, well-thought-out, properly maintained,fenced, rotated pasture, full to bursting with delicious grains and grasses. But no, no, as my original post said, these restaurants and businesses want to pass these cows over for the other. That's fine, you are welcome to it.
And for the poster who wanted some outside references, try looking up The Stockman Grass Farmer, The Omnivore's Dilemma, or, better yet, ask your local pastured beef farmer.