I find it rather strange that corporations cost you money, rather than gaining commerce from them. It doesn't make sense.
I guess you can think of it like modern day Franchises. The country gains much more money by having Franchises outside the US. All the profits made by a franchise go the headquarters, not the country the franchise is in.
For example, lets say the US invents a new product X and begins selling that within the US. How much money is the US making off this new product? Right, zero. Now, if you start selling this to Europe, you will make money because Europe is giving you money in exchange. Within the US, money is just changing hands.
Corporations are a financial tool in my opinion, and not necesarrily a production/food enhancement.