I'm not sure how a disk comes from the factory. In nibtools, I write all "0" bits to the disk on every halftrack, so no flux transitions at all. This shows up as "noise" to the 1541 because of how it works, but I have not tried to image such a disk with KF. I will do so in the next days to see which result this matches.
This is what a fresh, never used Maxell disk looks like imaged with GW and loaded up with SCP.
It looks just like the disk you show erased with KF, for comparison.
This looks also exactly the same as a disk from 'nibtools -u'.
Thsi looks also exactly the same as a disk erase with Greasweazle "erase" function.
The reason it looks like this is the AGC in the floppy drive amplifies the absense of any signal, i.e. it is just noise from the amplifier.
Note and remember that the floppy data seperator is designed for one thing only- to detect flux change. There are none here in any of the examples. The noise would never be detected as any kind of data, or interfere with it. It is "not there" like a ghost. The pattern will be different each time you read it.
I don't know what signal SCP is recording on here that would show it as different, but that is not how a new unused disk looks. I wrote a disk as all sync (nothing bit 0x11111111) and it showed up as the second attachment.
The 3rd attachment is from HxC Visual Floppy disk. Erased disks identical to the new one from the box.