but I feel like people in union jobs making enough of a salary to buy a comfortable home is going to drive up wages for everyone

Even if that is an effect where increased unionized non-supervisor wages push up supervisor salaries, my point is that there are simply fewer middle managers to benefit from that effect.

Plus the second order effects of a hollowed out middle choking out the pipeline for promoting and training future business leaders, so that it’s a small number of big corporate executives overseeing jobs they’ve never had instead of the older system of a lot more small and medium sized business leaders supervising jobs they used to personally work.