Yep, they were ground: you could definitely see the grinding pattern on the originals. On low-mileage ones, you can still see it on the edges where the pads have not worn it off, yet.
The pattern suggested they were ground, then mounted to the spoked hub, so I imagine a long line conveyor, passing under a grinder like a Blanchard, then someone flipping them over for the other side, then to the next grinder. Thicknesses varied from 5.55mm to 6.55mm on new ones. Honda says 5mm is the minimum, but mine is below that with no issues. I think they were just being conservative as it was the first disc brake out there.