Ian, you beat me to it, RossM obviously hasn't worked on a construction site. Testing & tagging of leads & tools also has to be done for any commercial workshop or factory. I've worked for customers who required it every month, which would be a big expense for a small business. Cordless are far safer, no cords hanging around everywhere (they're not supposed to be on the ground) & no risk of electrocution.
The latest cordless tools from the quality manufacturers are often equal or better performing than corded models & with Milwaukee (& possibly others) now having 12Ah batteries, run time isn't a big problem.
Even in my small workshop, not having to unravel a cord, making sure it's not caught on anything & having to roll it back up again, especially for a quick job, makes cordless a no brainer.