There's plenty of Big 3 dealers that advertise so-called "no-haggle" prices online. I think what you're saying is there are very few that unabashedly advertise no-haggle, 20+ percent off MSRP pricing online like Dennis Dillon (and to a lesser extent, Dave Smith) in Idaho.
When I was shopping all the Big 3, 1-ton trucks a year ago, Dennis Dillon's 20+ percent off MSRP online pricing enabled me to leverage an awesome deal on a Ram 3500 much closer to home (right there in Southern CA I might add--I live in AZ). I was shopping nationwide and just couldn't find discounts anywhere near this high on any Ford and GM trucks.
Good luck!