Warehouses? Hardly. The amount of infrastructure they have for gas & chemical handling and electrical, not to mention the positive pressure, air-handling, and probably low dust and effluent requirements should put them probably on par or above even hospitals and bio labs.
I'd expect most of their construction workers are going to be heavy equipment operators or specialists doing plumbing, HVAC, electrical, etc. I'm not sure if you've ever hired a house plumber or electrician, or know anything about compensation for heavy equipment operators, but it's a heck of a lot higher than the numbers you quoted for US average construction salaries.
Yeah, I'm not trying to argue in favor of the statistics cited in the article. I'm just saying that I think you can't just apply industry averages, when trying to estimate the costs, here.