..."sugar policy works to keep supplies stable and prices reasonable". You might add that it also makes a certain group of farmers wealthy and keeps their political friends in power. If true, this policy would be the first example of a planned economy that worked. I had always thought that planned economies were the road to serfdom. (I made that up).
There is no such thing as a true, laissez-faire free market economy.
The very existance of government influences economic decisions, and all government policies and activies impact the economy, one way or another.
Your use of the term "planned economy" is extremely naive and uninformed. U.S. crop subsidies, including sugar, in no-way resemble the "planned" command economies associated with marxist communism. Instead, they merely provide legitimate market incentives to assure that our nation benefits from a bountiful and stable food supply, rather than suffer from the natural cycle of "feast or famine" that is inherent in agriculture production.