In most cases, the original intent of the labor unions were fine. In any economic system there are those that will maximize their profits without considering the moral impact. For example, horrid working conditions, child labor, forced overtime without compensation, and worse.
But, greed and jealousy still rule the day. As the unions won their concessions, they continued to press and as a result, they became the immoral leaders—pressing the corporations (who were still focused on profit) to make THEM rich, at the workers’ expense.
If you look at most human issues, the problems of greed and jealousy will screw up everything.
I am not a fan of labor unions, as I have seen the corruption in the UAW. Husband has had grievance filed against him for silly, stupid stuff. But on the other hand, had my 61 year old father not been a member of a railroad union he would have been let go without his pension when his job was abolished. The union was able to make them find him another job for the 18 months he needed. Of course, that was 36 years ago. A lot has changed.