Small percentage of total workforce actually makes no difference to the principle.
If, in any single workplace or any single trade, there is mandatory membership of a union, then it will result in poorer quality service by that union (just like any business monopoly).

It's only 6.7% of the private workforce and I am not trying to convince anyone. It seems that most opponents feel that union members are dragged into membership and that maybe the case for some but not all. I was just making that point.

Maybe so. (though personally I would run from an offer with those kind of conditions)
Voluntary association would demonstrate very clearly whether ANY union activity represented good value. Thats why it is avoided.

I understand everyone's reluctance to support unions but in some instances it is a partnership. In trade unions the apprentice is trained for free with the understanding that he will work for the union.

Louis CK is an all knowing bore. He thinks A = Himself and all others should think what he does. President Obama call your office.

Incredible story!
If unions were based on voluntary association, this kind of ruling could never happen. But when membership is mandatory, thats when we get many unintended consequences. It is very similar to "monopoly" status in business.