There are definitely unions in the aerospace industry. My uncle was involved with a strike at United Launch Alliance a few years ago. It's actually the only time I can remember any member of my family going on a picket line.
Disclaimer: I applied for a low-paying SpaceX IT position in Cape Canaveral, because Mars.
Ariane also has to deal with unions. You can see direct evidence at http://www.space.com/13037-ariane-5-launch-postponed-labor-s... .
(I mention these because strikes are easily reported in the news. Behind the scenes of course many of the engineers who built Ariane and the Shuttle are union labor, but that fact doesn't have the conflict that brings in readers.)
Since I don't see how union labor implies what you think it does, could you clarify?
Edit: Come to think of it, Elon would be very very happy if rocket manufacturers really had to deal with union the way car/plane makers do. That would mean rocketing across space is really like getting on a jet liner. But we all know that's many years away.
So yeah, union/non-union is a non-issue for SpaceX.