Where the analogy of corporate personhood breaks down.

I've often thought about why corporations tend to do things that if a real person did them would be considered at best unpatriotic and at worst purely evil. Then it occurred to me: while the legal fiction that a corporation is equivalent to a person has its uses, the analogy breaks down when it comes to such qualities as moral intention/motivation, citizenship/nationality, and so on. ( Corporations aren't people. )

How, then, do people empower themselves in the face of corporations? I'd be interested to know.