The gross statistics back it up. The average American eats about as much seafood as the average Russian, which is surprising considering one has ample fisheries and coastal areas and the other doesn't. Both countries are about mid-line per capita globally at something like 20-30 lbs (9-13 kg) per person per year (vs 60-80 pounds (27-36 kg) for countries like Korea, Japan, etc.)
More detail, if you look by locale in the U.S. the average Midwesterner eats something like under 1/4th the seafood of their coastal countrymates. That's not 1/4, that's again less than 1/4th so we're talking from zero to 7.5 pounds per capita.
Since population distribution in the U.S. is heavily skewed towards the coasts, you can estimate that for example, the average of 20lbs per person per year is representative of the average coastal person. This means that the average Midwesterner eats less than 5 pounds of all types of seafood per person per year or about something like less than 1 small shrimp per day.
The thing is, modern logistics make it possible to eat fresh Sushi in the middle of Kansas. Being away from the coasts isn't really an excuse as the availability is or can be approximately the same.
*sources: something something forgot to copy paste use the google or DDG it's like 2 minutes of searching plus some math
Flash freezing is relatively new technology (I assume that’s what you mean by “fresh”). It is not surprising midwesterners go all out on sushi (the real kind, not Californian roles) just because the logistics are easier now. Food is local because it has been that way for the last hundred or so years.
The miracle of the National Highway System makes Boston to San Diego a 50 hour possibility. Surely the people of Springfield Missouri would be fine with iced, fresh, 20 hour old fish caught off the coast of Connecticut! You can get an entire boat of fish from the Gulf Coast to Kansas City same day by road.
Delaware to Louisville is what 8 hours? But why bother, fresh mussels from Lake Erie don't even have to leave the state, can by caught in the morning after breakfast and eaten for lunch a couple hours later.
The Highway System is almost a century old. That's a few generations time to change preferences.
Because everything undergoes flash freezing in the boat anyways, 8 hours or 8 days isn’t going to matter much.