Comment # 132 on bug 920937 from Johannes Meixner

FYI regarding the issue that
running plain /usr/lib/cups/backend/usb as root shows a USB printer
but "lpinfo -v" and the CUPS web frontend and other printer setup tools
do not show it:

It seems bug#938659 shows the root cause:
"udev does not set 'rw-rw-r-- root lp' for device node for all USB printers"
see in particular
https://bugzilla.suse.com/show_bug.cgi?id=938659#c4

Perhaps it works for Ian Powell because he got a newer udev
but I am not at all a sufficient udev expert to really know.