Labor unions have been destroying themselves and the businesses they infest for the past several decades. They don't need any help from me.
And yet the greatest growth in living standards and GDP occurred when labor unions were strong, and the decline in the rise in living standards corresponds to the decline in the percentage of the work force which is unionized.
Association and cauasation are not the same thing. The major growth of American industrialization (and that of other countries as well) was the real driver for the rise in living standards in this country. The labor unions that followed that growth were indeed a beneficial counterforce to some serious excesses and inequities that accompanyied that rapid growth. However as the biologists say "the poision is in the dose". A moderate level of unonization, focused initiaslly on the firms involved was indeed beneficial. However when the idealogical element of classs struggles was added , along with industry-wide monopolistic unions orgsnizations,seeking to control access to jobs emerged, it became a destructive force that eventually crippled and destroyed the industries it infested. That lesson is very clear in our history.
Labor unions are associated with increased living standards for the middle and working class, much to the conservatives' distress, because they raise workers' salaries, who then spend the extra money they get and produce more jobs for more people at higher wages. It's called the multiplier effect, and conservative, classical economists and their minions haven't figured that out yet.
Competition for workers does indeed raise salaries and deliver the multiplier effect to which you referred. However, labor unions - as the high salaries now prevailing in the union-free Tech. sector amply demonstate - have nothing to do with that, and conservartive economists are well aware of both phenomena.
And the concept of labor unions keeping minority workers poor is just laughable, unions serve to raise the salaries especially of non-college educated workers, a class in which minorities are somewhat over-represented. Take away union jobs in such things as highway construction and Federal project construction, and black America is going to take a huge, huge hit.
I believe you should get better informed about the history of labor unions, partiucularly the UAW in the early 20th century and that of the building & construction trade unions today. Blacks were only very reluctantly given access to UAW memberdship and that after a long struggle. Indeed the union worked to keep them out of the early auto industry. Today's situation varys a bit with locality, but the bulting & construction trades do indeed restrict membership through their monopolistic contracts ( sometimes Mafia connections) and government protections, and they do indeed limit the accrss of Blacks to such jobs. When is the last time you saw a Black carpenter or electrician??? I'll agree ther situation is quite different in other union groups.
Another phrase I like from biology; "Intelligent parasites don't kill their hosts." Contemporary labor unions are parasites, but not intelligent ones: they kill therir hosts -- as the situation in our public schools visibly attests.