Japan has 50% more coastline than the United States.

Where I sit, 1000km from an ocean, seafood is pretty remote. Sure, it gets flown in and flash frozen isn't horrible, but it isn't fresh.

A lot seafood is flash frozen these days, even next to the coast and even in japan. It’s just the best way to deal with parasites. I don’t think you can eat sashimi in the USA that hasn’t been flash frozen.

lake/river fish usually have parasites and must be cooked.

I was under the impression that ocean fish don't have the same level of parasites.

You would never eat a catfish raw.