Why not? Bulk shipping is really efficient, local farmers markets can easily be worse for the environment than going to a supermarket. A Semi moving 35 tons at 7 MPG is 25 times more fuel efficient vs a ford F-150 moving 1/2 ton at 20 MPG and trains or boats are even better.
In the end fuel costs money so more efficient logistics is often good for the environment. Buying local makes a lot more sense if you live in a farming community than a port city.
In a previous job, I did the math for shipping goods from Melbourne to Perth here in Australia via freight train. It worked out to be 1 litre of fuel per ton moved 500km. In imperial, that is 1 ton at 930MPG! That efficiency is mind blowing but it does rely on a lot of goods to be moved to gain that scale efficiency.
Replacing shipped blueberries with locally farmed ones definitely could be a wash or a loss, environmentally, for sure I agree there. But we have relatively efficient industrial scale farming in the US as well, if we admitted that blueberries are seasonal we could grow them in big efficient farms and then just ship them less far.
A lot of fruits freeze pretty well too. When I'm in Maine at the right time of year and big boxes of "wild" local (low-bush) blueberries are for sale, often they're already frozen. I agree that local fruits during their short local season can be pretty good but stuff that's shipped in or frozen isn't necessarily bad. Depends on the produce.
In the end fuel costs money so more efficient logistics is often good for the environment. Buying local makes a lot more sense if you live in a farming community than a port city.