When produce is in season the relative abundance makes it cheaper. It’s the basic law of supply and demand.
When food is not in season locally, it’s either grown in a hothouse or shipped in from other parts of the world, and both affect the taste. Compare a dark red, vine-ripened tomato still warm from the summer sun with a winter hothouse tomato that’s barely red, somewhat mealy, and lacking in flavor. When transporting crops, they must be harvested early and refrigerated so they don’t rot during transportation. They may not ripen as effectively as they would in their natural environment and as a result they don’t develop their full flavor.
Save our environment!
Importing produce is bad for the carbon footprint of your household! Think of the distance it’s had to travel to get to your table! Depending on the location of origin it’s also possible it’s been treated with chemicals before being exported.