C-channel straightening machine - GIF

[Frank S]

That's still a pretty poor C channel.

It begs the question - how much crappy C channel is there that they built a special machine to mostly straighten it?

Probably didn't build a special machine. Just take any 6 to 9 stations roll form machine capable of forming at least 1/8" sheeting. Change the rolling dies to suit the task then straighten the C channel.
The problems would be when there are weldments on the channel