Yes, corporations more or less run America, but they run it mostly via their Republican shills.
Do you think that Republicans would ever have pushed for Social Security or Medicare or any other program that benefits average Americans?
Do Republicans champion voter rights? But they do push for massive tax breaks for the super rich.
Sure, Democrats are a mess, but they are all the average American has on his and her side--mostly.
Republicans are masters at playing one block of Americans against the other via fear and hate to the advantage of their corporate masters.
It is easy to throw up one's hands and say that the major parties are all the same (Democrats and Republicans), just what the fat cats hope voters will do--screw themselves.