Hmm... this looks interesting:
$ /usr/lib/cups/backend/usb DEBUG: list_devices DEBUG: usb_find_busses=8 DEBUG: usb_find_devices=12 DEBUG: Failed to set configuration 1 for 04b8:0005 DEBUG: Failed to claim interface 0 for 04b8:0005: Operation not permitted
$ sudo /usr/lib/cups/backend/usb DEBUG: list_devices DEBUG: usb_find_busses=8 DEBUG: usb_find_devices=12
Hmm... this looks interesting:
$ /usr/lib/ cups/backend/ usb
DEBUG: list_devices
DEBUG: usb_find_busses=8
DEBUG: usb_find_devices=12
DEBUG: Failed to set configuration 1 for 04b8:0005
DEBUG: Failed to claim interface 0 for 04b8:0005: Operation not permitted
$ sudo /usr/lib/ cups/backend/ usb
DEBUG: list_devices
DEBUG: usb_find_busses=8
DEBUG: usb_find_devices=12