It still happens because, when your seeking that viral edge sometimes the cost benefit analysis turns out in favor of pissing off a certain percentage of your members.
As far as the ethics involved, I don't really expect corporations to be ethical at any level. I would like them to, but I don't expect them to. I am a strong proponent of extreme fines/legal action because really if it doesn't effect the bottomline I dont feel it will change behavoir of a business.
A corporation is just a group of people. It's not possible for a corporation to be ethical or unethical, a corporation doesn't have a soul or a conscience.
It's possible for specific people inside a corporation to behave in unethical ways. However, the definition of maximizing shareholder value is not simply "make the stock price as high as possible in the short term." It's perfectly possible for executives in a corporation to take the high road as the optimal strategy for maximizing shareholder value.