Go ahead and read this article by David R. Francis about the decline of union influence and every place he writes about how much "corporations" are benefitting, just replace that word with "shareholders". And remember that half of American households own stock.
I support the right of any group of workers to unionize, but I also support the right of employers to fire those workers and replace them with other workers, if they can do so. The power of organization should come from the value of the workers themselves, and the value of the workers depends on the price their labor can demand in a free market. If someone else can do the work better or cheaper, why should we have laws that require the employer to employ less than the best?