Thirty years ago you could only get certain produce items at particular times 
of the year. This has gradually changed over time as countries around the world have started growing fruits and vegetables, improving varieties, increasing volumes and exporting to countries such as the United States.
In 2011 the leading suppliers of veggies to America were Mexico, which accounted for 58 percent of imports, Canada 27 percent and Peru three percent. The top countries providing us with fruit was Mexico 34 percent, Chile 20 percent and Costa Rica 11 percent.
In most cases if these countries were not providing us these perishables, these items would not be available at all, or least in much less limited supplies, which would greatly increase the costs we pay for them. Their growing seasons differ from ours.
There are some exceptions, with perhaps the most drastic being the tomatoes available to us from Florida in the winter, which compete against tomatoes coming out of Mexico. Over the years the Florida tomato industry has complained out Mexico undercutting them on price and flooding the market with excess supplies.
There is some truth in these claims. At the same time, you’ll find Florida providing your supermarket with mature green tomatoes, while the Mexicans are supplying us with vine ripe grown tomatoes and in more recent years have greatly increased their greenhouse grown tomato supplies.
Outside of the folks who grow mature green tomatoes in Florida, I find it difficult to find people who like the taste of these tomatoes, especially when compared to vine ripe and greenhouse grown products.