Excellent epistemic inquiry. I’ve owned homes for over 30 years, and have experience with hiring contractors for remodels. Also hired non-union contractors to do building work on offices over the years. And the company that had a machine shop? One of our channels was home construction and overall I was not impressed with the kind of work I encountered.

But to really get to your question: I started my 3-year home construction odyssey with a non-union contractor who had to be fired due to poor execution. The replacement was a union shop. That’s about as much A/B testing as one can get.

So you had one bad experience building a home with a non-union contractor and extrapolated. Seems sound enough.