No it isn't.
I have been desperate for work many times in different states and cities, and I have been offered union membership, I have always refused it.
I can tell you of the most horrible sales pitches, things like "they can't fire you", "once you make it, you don't have to do anything", I was the guy that always preferred commision based on what I produced, unions are not for the independent man.
Job I took mandated union membership - no choice.
I lasted 9 months, then found another job. Some nice folks but a whole lot of idiots & the work rules were just nutz.