Spent a large part of my professional career in the business of building stuff that handled, transported, or maintained things that go boom, along with some things that went boom on command and yet even more things not intended to do so, but perfectly capable of going boom if not handled correctly.
In short, the lives of a lot of people depended on us getting it exactly right every time.
As you might imagine, the bulk of this was done for our Uncle and if it had potential for disaster, union labor was required to build it. This was not because some senator was paying back unions for their support it was because unions had their own set of internal competency testing procedures which insured a consistently higher quality product with a near zero scrap rate. Each individual part had to be traceable back to it's fabricator and every weld had to be traceable back to the guy who actually ran the bead, and union labor was always capable of providing sufficient numbers of properly qualified and experienced hands to get the job done within the scheduled time constraints. We (management) handled scheduling and logistics and such, and the union took care of insuring we had enough of the right people to get the job done with a reasonable expectation of a job done right the first time.
Would you prefer an experienced journeyman building your MIRV ground transport pallets and nuclear reactor cores, or would you be Ok with some high school dropout with a low grade meth habit and 3 months of OJT as a helper doing it?
I once ran a CNC machine shop where the only persistent problem I had was convincing upper management that hiring "button monkeys" fresh off the grill at the local burger joint was not a good idea.
There is still plenty of need for union labor. Unfortunately abuse of union power and relentless negative PR from those who have everything to gain by seeing unions scuttled have made it a rather hot topic these days. Attempting to paint all unions with the same negative brush is as disingenuous as trying to sell the idea that all unions are good and have only the best interests of their members at heart.