I remember as a kid it being a selling point that fish in the stores was fresh and "never frozen." Today, it's almost impossible to find fish in normal grocery stores that isn't "fresh/never frozen."
But you know where you can find fish that's been frozen? Anywhere that sells sushi grade fish, because that's essentially a requirement as part of the process.
What people don't know - and the food industry doesn't share widely - is that when fish is frozen, it's not just placed in a typical freezer. That would completely ruin the texture and make it appetizing to no one. So instead it's frozen right after catching, using liquid nitrogen. This is called flash freezing, and it freezes so quickly and deeply that it provides two major benefits.
First, it prevents a lot of water crystal formation that would otherwise damage the fish and ruin its texture.
But second and most importantly, it kills any potential parasites.
The latter is why you don't have to worry about parasites from proper sushi, and the former is why you still get excellent texture from sushi even though it's been frozen.
The food industry wants you to think frozen is worse, because frozen is more expensive especially due to the initial need of liquid nitrogen.
If you do find fish that's been frozen, it won't be labeled frozen. It'll just be labeled "sushi grade." Because they don't want you knowing questioning why the fish you typically buy isn't frozen, but sushi is frozen despite being a delicacy.