planet money had a podcast on it years ago that has stuck with me- they were talking more about frozen food, but it probably applies. The gist was that sugar, fat and salt can mask crap ingredients. The reason that you don't see low priced healthy food is that with out the salt/sugar/fat people would realize just how bad the ingredients were and that decent ingredients push the price too high to be viable as replacement for the current stuff
I think it was anthony bourdain who wrote in kitchen confidential that chefs always load up dishes with salt, butter, and fresh herbs to make them taste good, and that you could easily do the same thing at home.
This is one of the reasons I LOVE Seasons 52 (also a Darden property I believe), they make fantastic food without any fat and with limited salt.
It's amazing that Darden owns S52, Bahama Breeze and Capital Grill, all of which are very good, and they can't fix Olive Garden.