There's another thread asking if there were cliques in the congregations.
Your experience, which is similar to mine when it came to quick builds and other construction projects provides an affirmative answer to that question.
The 'brothers' who were tradesmen banded together in their 'all-he-men-of-the-construction-trade club' and guarded their position and territory like a junkyard dog. I think one reason was that if they were busy building/remodeling then they could rationalize not going out in service. It was as if their attitude was, "Let the soft-handed and computer geeks go out in service. We have hard he-man things to do".
I worked in the construction industry at the time but didn't really go out of my way to offer my services for every RBC project, even though I got the letters. When I did show for a local one, they didn't use me in my particluar trade. One time I showed up at a quick build with my tools and was put on the brick line... you know, the line where the kids and sisters stand in line and hand bricks one by one from the pallet to the bricklayer.
Another time, after developing another trade, I was actually put on a task that used my new skills...except the so-called 'brother' in charge was a grade A large asshole. He went around barking orders and yelling when he didn't like how things were done. A substitute CO had to pull him aside and remind him of where he was. He toned down...until the other brother left and he went back to his slave driver ways. That was my last quick build. If I'm gonna get yelled at while working, I'm gonna get paid for it. I ain't doing it for free.
To be fair, my experiences were from the earlier days. The early quick builds were a free-for-all. Everybody - skilled, unskilled, coordinated, uncoordinated, smart, stupid, adult, child, man, woman, showed up and it was a clusterfuck. People in each others ways, painters in the way of electricians, etc. People not used to being on a construction site and getting in the way. Kids running around. Over time, they refined the process and by the time I had left they were using only people skilled in the trades needed, plus a volunteer group to feed them.