Back when I was in the roofers union (did my 20 years in hell), one incident turned me against unions forever. I worked for a very large company (100+ employees) that did nothing but commercial & industrial flat roofing on mostly new construction, all over N.E. Illinois. A store like a K-Mart or Walmart was a "small" job for this company.. we did most of the shopping malls, we did McCormack Place. I was the foreman of the "set up" crew. I had a crane (with an operating engineers operator), and a dozen guys. Our job was to stock a roof deck in preparation for the installation. We'd space the roofing material out where it needed to be for the installation, using 4 wheel carts to haul pallets of roof material lifted up by the crane with a pallet fork, which we unloaded by hand.
We always installed insulation over the roof deck as the first step. I was setting up a job on a large new warehouse project, and 8 semi-loads of 2" thick, 2'X4' foam insulation were to arrive that day, coming from Mansfield Ohio to the jobsite in a N.W. suburb of Chicago. Unbeknownst to us, the plumbers union went on strike that very day, and pickets were set up. We were told we could not cross the picket lines by the plumbers BA. I called the company I worked for, they said bullshit we weren't informed of any strike, do your job and put the insulation on the roof deck. Tell them we'll honor their picket lines and it won't be installed until their strike was over, but we cannot just "send it back" to Ohio. It was a fair compromise. Their union never informed our union of any impending labor action, which they were supposed to do... if they had, we would have held up the delivery before they left Ohio the day before.
I politely informed the plumbers BA that we cannot just send 8 semis back to Ohio, we weren't informed prior as was customary, there wasn't room to just unload the cargo on the ground, that we were going to put it on the roof, but nothing will be installed until their strike was over. The general contractor's rep was by my side, trying to explain to the plumbers that we were in effect honoring their pickets by not installing the roof material, but the financial loss to my company was unacceptable if we didn't unload it. Plumbers wouldn't budge, got nasty, names were called etc. Fuck 'em. Cops were called by the general contractor, and we did our job. The semi drivers, all members of teamster union, backed our position. They actually stood guard over our private vehicles, because the plumbers threatened flat tires etc. It was ugly, two of our BAs came out, got nose to nose with the plumbers. Left a bad taste for union bullshit that I never forgot.