I don't think it's so much that people believe corporations have a legal obligation to seize all opportunities for profit, I think it's that many corporations have been behaving in ways that the majority of the population believes is, or should be illegal. The people in charge of these companies are fully aware of the public perception of what they do, but they continue because they know they can get away with it with a few financial donations to some political campaigns here and there.
I don't think the vast majority of corporations do what you suggest. On the whole, IMO most corporations (private and public) contribute to the economy and society without being scoundrels.
