[Morrigoon]

There's a big difference between corporate shareholders and union members: the unions are "run" actively by their membership. On the other hand, corporate stockholders are what is known as "limited" partners in the business. Their contribution is limited to their investment in the company, and as we've seen with Disney, their power to control anything else (such as the board) is severely limited. For that reason, I could see wanting "active" membership to have a say in how their money is spent, whereas shareholders have already subjected themselves to a position of non-control.

Now, if you wanted shareholders owning over 5% of a company's stock to vote on something, that would be okay because they generally have more power in a company and ought to have more say in how it's run.