To be fair sushi is quite a particular taste if you don't like raw fish well then you won't like 95% of sushi. What I was getting at was if most of us here on FT saw a local Italian trattoria and on the other side of the street was an Olive Garden, then we'd probably take the Olive Garden. At some point middle America appears to have said nup I'll take the chain.

I think from what I have read here the most likely explanation is that in many smaller cities good food was hard to find, so while TGI's etc may have been nothing special in the big cities it was refreshingly different from the bad Chinese restaurant or diner and they gave big portions at good prices. So people started going to chains and then they just got comfortable with it so they never went back.