I am curious why you think our choices are being restricted as to what we eat.
And
Food is often less expensive than ever before in history.
Ok, first, try to buy something that doesn't have corn in it and corn that's not geneticly modified. If you're successful in that, try the same with soy beans.
Some folks may point to a grand conspiracy but the reason, I think, is more related to your comment about the price of food. That would be because both soy beans and especially corn are highly subsidiezed. So what you don't pay at the grocery is made up in taxes.
I can go to a local convience store and get a 44 oz soda for 69 cents. Why? It's because high frutose corn syrup is un-naturally cheap.
What we'er ending up with is an industrial food system that cranks out more empty calories and less nutrition than ever before.
And as far a choices go, where do you get your raw dairy products?
Potatoes. Rice. Flour. Beans. Carrots. Peppers. Meat. Fish.
I could go on, but I'm sure you get my point.
You are quite right about processed foods, which was pretty much my original point. If you are willing to prepare your own food from staples, as (non-rich) people all used to do, then you can avoid corn and soy.
If you want the convenience of prepared foods, you will take what the market assembles.
The price of corn went up a bunch a couple of years back due to the idiotic policy of making auto fuel out of food. Resulted in a bunch of pissing and moaning by liberals about how poor people around the world were being starved by greedy American agro-corporations. Then the price went down, and the same liberals pissed and moaned about poor Mexican farmers being driven off their land by cheap American corn.