That said, why did they go to Bell Labs rather than a building constructor in the first place?

I don’t know the real answer, to be clear, and I had the same question when reading the story. But I suspect the answer is a combination of prestige (everyone wants to work with bell labs, not John smith of idahos metallurgy shop) and connections (someone at bell labs knew a local politician who knows a guy who knows a NPS worker in that team).

That’s usually what everything is.