In The USA: the Next Revolution

[Fuchs]

If the absence of unions is perceived as a market distortion, what would you call the presence of unions that are capable of shutting down an employer who doesn't give them what they want... perhaps looking at Britain in the late 70s as an example? Is that not an equally distorted market?

It is. Power asymmetry can go both ways.
Countries can balance the powers or employers and labour unions through legislation, jurisdiction and culture, though. I think that's what all developed countries should strive for - and it's an everlasting challenge.

Btw, slightly related to topic (UK, not U.S.):