It sounds generic, sure, but it's a nod to DC history. They started out as National Periodical Publications.
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It's set in the DC universe, where all those cities exist. Marvel uses real cities, but the drawback to that is you have to try and keep things in sync with actual reality to a degree.
The first Spider Man movie was affected by this, when 9/11 happened and they had to remove all scenes with the twin towers, including the scene with the helicopter webbed between them.
In the DC universe, they're free to do whatever they want because the cities are fictional, real world changes don't matter. They could totally destroy Metropolis if they wanted, make it completely unrecoverable. You can't really do that with New York without making it into a different show altogether.
Tommy how's the peeping?

National City is indeed a very generic name. I know this is fantasy but I thought this wasn't 1993 either.

And then you have Seattle
You're suffering from delusions of adequacy.
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Keystone City and Coast City too.

It's a DC comics thing.
Gotham City, Metropolis, Central City, Star City, National City.
No real American city names. The Vertigo shows (Lucifer & iZombie) use real city names.

I don't know how I feel about LA being national city. Using LA as a stand in for any city just screams, "this is a business, not an art!"

Well they can easily digitally edit stuff in, and use shock shoots of LA from season 1. Heck why not blue screen back shoots of LA using season 1. I don't know.

It stinks, suddenly most of the action occurs at night.
Where are the Asian characters DC CW? #MoreAsians

Lesser taxes in Canada, that's why.
In vino veritas

It's shot in Vancouver now because the show switched networks.

Why? That's ridiculous, they already established it as LA. They didn't just slip in a few landmarks by accident, they showed the entire beep skyline every 5 minutes, along with palm trees and brown dusty mountains. They just beep up the continuity big time with Vancouver.

It's actually filmed in Vancouver now.