There simply is not the capacity in the seed industry to produce all of our vegetable seeds and to make a profit. Our market is too small. The downside is that we accept varieties that may not be perfectly suited to our climate, environment, diseases, and insects in terms of resistance. Again, the economics aren't there.
However, if you're in the corn, soybean, wheat, or barley business, absolutely, there's a big seed industry, and they are producing seeds with the kinds of genetic backgrounds that are profitable for our growers.