Instead of adding opacity to the system, I would rather they remove the subsidies instead.
I understand the appeal ideologically, but in practice what you are suggesting would increase inequality.
Humans should end their diary addiction, it would help with obesity, and a whole other host of health conditions.
However, this is not done as it's more difficult to corrupt and profit off of this since it is transparent how much help the poor are getting. It's easier to muddy the waters and steal from taxpayers by creating a byzantine system of tax breaks and subsidies.
If you're referring to agriculture disappearing from the US, that definitely wouldn't happen either. Some of it might, but not the majority. Most countries don't heavily subsidize farming to the extent that we do, and transportation costs are non-trivial, especially for fresh produce or anything that needs freezing.
https://en.wikipedia.org/wiki/Agriculture_in_New_Zealand
Edit: The thing I found most interesting about this is agriculture was deregulated by the left wing government in what is a very socialist leaning country. Kiwi's are very pragmatic.