... why the government is involved in this issue at all.
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Easy answer: the various food lobbies have money. Elected officials have a strong appetite for money. That money changes hands and rules get generated.
This isn’t rocket science. It isn’t even nutritional science. It’s political science.
It’s also about cost control...in Uncle Sam’s mind, if he’s going to fund Medicare and Obamacare, then he believes that he has a vested interest in forcing people to be healthy so that he can ration it.