>> But there is a difference! Stuff shipped a long way costs more in shipping, so they'll ship the best stuff, because the can charge the most for it
This is not always true. If the "best" is delicate or easily damaged they sell it locally at a big discount and ship the tougher ones further. A good example is lobster; the best is sold cheaper near where it is caught while the oldest, toughest and most durable is shipped around the world at a huge premium.
It makes no sense in these terms I agree, but the produce in NYC absolute does suck compared to SF. And the restaurants likewise barely with dishes emphasizing vegetables either unless you shell out a lot of money.
It takes exactly the same effort and time to pack something for 100 miles as for 1,000 miles.
But there is a difference! Stuff shipped a long way costs more in shipping, so they'll ship the best stuff, because the can charge the most for it.
So actually far away places get the best produce, and CA is left with the cheaper stuff that isn't worth selling far away.