The government should always have control over food prices.

 When you let the greedy corporations increase food prices, those corporations will earn 2/3 times more profit each year. What will be the impact on the rest of the country? It will collapse.

People's earnings are very limited. They had to buy food to survive, no matter how much it cost. So, they won't invest money on clothes, furniture, travel, restaurants, or any other issue, no matter how much they need to have those. So, these companies will go bankrupt. The country won't get enough tax money from the organizations. 

The big corporations making billions of profit have big lawyers to find loopholes to give tax. The general people, who earn very little, give taxes. The government can't ignore these people.

So, finally, the government will collapse.

That's why the government should always have control over food prices. There is no place to show greediness on essential items of life.