It's not always that way. There are large fowl out there with better barring than the bantams. The problem is that a lot of people have the production barred rocks from hatcheries and they don't breed for good barring.
It is indeed hard to find LF barred rocks with good barring but they are out there. I have to say that I see a lot more bantams with good barring than standards when I attend a show. I raised both for a while but right now I just raise, breed and show bantams.
Yep, like they said, few people have Barred Rock bantams and the ones that do, usually have some from show lines that have been bred for correct barring, color, and type. There some nicely barred LF Barred Rocks, but most Barred Rocks are from hatcheries that just breed what ever lays and pay no attention to type and color.
Is it because people are more likely to get bantam barred rocks for showing than they are with large fowl? I know when I think, "barred rock," I think eggs, not exhibition. They're a popular egg laying breed around here, though everyone calls them "dominekkers." No one cares what they look like as long as there's an egg popping out of their butt.