Comment 3 for bug 993728

Interestingly, my 70-persistent-cd.rules exists, it's just effectively empty:

$ cat /etc/udev/rules.d/70-persistent-cd.rules
# This file maintains persistent names for CD/DVD reader and writer devices.
# See udev(7) for syntax.
#
# Entries are automatically added by the 75-cd-aliases-generator.rules
# file; however you are also free to add your own entries provided you
# add the ENV{GENERATED}=1 flag to your own rules as well.

I wonder if Ubuntu didn't properly detect something when it was installing itself? For reference, here's the pertinent output of some of the commands you mention, from my machine:

$ sudo lshw -C disk
...
  *-cdrom
       description: DVD-RAM writer
       product: BD-RE WH10LS30
       vendor: HL-DT-ST
       physical id: 0.0.0
       bus info: scsi@3:0.0.0
       logical name: /dev/sr0
       version: 1.00
       capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
       configuration: ansiversion=5 status=nodisc

$ ls /dev/disk/by-path/
... pci-0000:00:11.0-scsi-3:0:0:0

$ ls -Al /dev/disk/by-id/
...
lrwxrwxrwx 1 root root 9 Jul 9 23:38 ata-HL-DT-ST_BD-RE_WH10LS30_K97A3NA2854 -> ../../sr0

Does any of that matter? I doubt it. I'd have to check specifically, but I'm fairly certain I get the same problem on all other machines I use.