Have you ever been hired in a non union job?   They all either have set wages or negotiate wages individually.  As far as whether they do it fairly or not, that may be open for debate.
As far as unions sending over well trained workers, well that is also debatable.  Was helping with a build of an Applebee's in Fremont, CA, we had to redo all the woodwork with a non-union carpenter after the union carpenters screwed it up.   Well trained indeed.  
 Another way that companies get away from the 'core' purpose of hiring is to outsource it to temp agencies and companies that are set up just to do the hiring.