1. Most people want to purchase wines for under $10. The cost of production for a $10 bottle of wine is about 2.40 according to this article. (I’ve seen $3-$5 mentioned as a ballpark figure as well) The rest is marketing, transportation, distributor and retail markup. By contrast, the cost of production for a $100 bottle of Cabernet Sauvignon from Napa is around $30 according to this post. These numbers will fluctuate according to the unique circumstances of each winery but I think they are roughly correct. The cost figures for the $10 wine don’t allow for much focus on quality.
2. Supermarkets must purchase wines from distributors who have little incentive to sell interesting wines. Sales people prefer to focus on their best sellers because it makes the logistics of their job easier. They prefer to deal with wineries large enough to supply all their accounts and who enjoy an established reputation so the wines sell themselves. There are exceptions. Some smaller distributors and many, many importers work very hard to find interesting wines. But supermarkets have little incentive to make space on their shelves for these smaller distributors because it requires more communication, more paperwork, more attention, and more hassles. Again, there are exceptions. But not many.
3. Big wineries, the only ones most distributors will work with (see #2), do market research before they produce a wine. Their market research tells them people want smooth, lush red wines with a bit of residual sugar. So that’s what they make. Those large wineries make about 90% of the wine sold in the U.S. Producing wines of difference and distinction makes little sense because casual consumers lack the training and experience to recognize those differences.
The supermarket is where you buy wine to wash down food. If you’re interested in learning about wine you can get your feet wet there by beginning to learn about the most popular varietals. (Some Whole Foods outlets are good, Trader Joe’s tries harder than most, and Costco takes some pride in their wine program.)
But at most supermarkets you very quickly run out of interesting options.