If I understand correctly, one of the major reasons that corn syrup is so popular is that it made corn syrup cheaper than sugar.  This makes sense to me. However, it seems odd to me that this never really happened with corn flour/cornmeal vs wheat flour. While they definitely taste different, they still can often fill similar roles, and assuming that corn flour was cheaper, I'd expect it to gradually take over recipes in the US. Was US-subsidized corn flour not cheaper than wheat flour? Was there another reason corn flour didn't take over? (I'm obviously not talking about countries south of the US, where corn is everywhere) 
They are functionally quite different.  Corn flour does not contain gluten, so is not useful as a direct substitute. It has little to nothing to do with cost. 