a business owner in a non-union shop would be quite foolish to promote or demote based on "I like you" or "I don't like you". And successful business owners know that.
So if you already say this isn't a problem, what purpose does the union serve?
The particular successful business owner has learned or knows that by treating his employees fairly, with integrity and respect he will, in all probability, never have "union" problems. Unfortunately, there are still business owners who have yet to learn this lesson. Hence, there are still unions. And the term "successful business owner" means more than simply being profitable. There are degrees of "success" and different connotations. As an example, I would point to the current "problems" that Wal-Mart is addressing with its Black Friday employee protests. Not for one second would I imply that Wal-Mart is not a successful business, but some of their employees certainly believe that Wal-Mart is not treating them fairly, with integrity and respect. In the example you quoted, I was referring more to the small business owners instead of the corporations and large blue collar factories. I should have made that point more clearly. I apologize for not doing that.