I tend to lean more that it's based on farming... think of the name "US Dept. of Agriculture". It is only after I became interested in natives that I realize how messed up our government is. And I am not thinking of politics so much, though it might play into this. But how the different entities must be fighting against each other to get what they want done. There's those related to development and agriculture and those related to conservation that would seem butt heads with each other.
Now the Road people plant native seeds in areas they've cleared in the ditches. But today... grrr... there they were spraying the ditches, likely with glyphosate. Why do they do that when there is a wind from the east? I ran out and doused the natives in my yard that might have gotten the chemical drift. And they went by so fast, I cannot believe they were very selective.
Look at the Legal Status of the Common Milkweed on the USDA site!
http://plants.usda.gov/core/pr...
In some areas the Common is what grows the easiest, which is ideal for the Monarchs, yet teaching people it is a weed is not helping anything. I guess moving out here changed my view of farming quite a bit, much of it negatively. But I was encouraged earlier this year when two farmers we know actually said they were leaving the Common Milkweed alone. There is hope that change will occur, even if slower and in a different way than I'd like.