This is a false dilemma. There are plenty of publicly listed companies that also engage in moral behaviors. Pretending it's an either/or situation only serves to excuse the behavior and derail the discussion.

We should support companies that act morally, and punish others by not buying their products and criticizing them.

But expecting them to act morally out of their own volition seems foolish to me. Note also that I explicitly said publicly traded companies. Large ones always have a diverse ownership structure with institutional investors. A CEO that hurts profits by acting in the public interest will probably be replaced pretty soon, forced to fall in line, or have to otherwise do enough to offset.

The only way to motivate them is external pressure or benefits.

Eg Apple has probably decided to focus on user privacy to provide a contrast with Google and the Android ecosystem and maintain a good relationship with customers, not because privacy is "good".

The situation is somewhat different with private companies, where there are few owners that can actually have an impact.

Care to share some hard evidence to support that? Privately held companies certainly have some more freedom in their actions, but public corpos are a slave to the shareholder.

Public corpos only incentive is to create value for their shareholders.

Your elected government is illegally recording my calls, unless you believe the post-Snowden claim that they stopped (and there isn't any reason to). Why should I expect ethical behavior from this entity? I'd rather choose which software I route my data through than have the government "regulate" all of my options to include Clipper chips. I don't want the government to have any say about what I do with my data.