You bring up a major downside to industry-wide unions in that a single bad decision by a small group of people can make it so that an entire industry can suffer

You bring up a major downside to industry-wide unions in that a single bad decision by a small group of people can make it so that an entire industry can suffer, rather than many entities battling it out with a variety of decisions, which would give employees choice, and give some opportunity for the best decisions to win out over time. Perhaps the problem is not unions, but monopolization of an industry's workers by a single union.