So my parent's nexus 5 is currently on 4.4.4 and I want to upgrade them to 5. When the initial 5.0 OTA was released they told me they got the notification to upgrade to 5.0 but they didnt update because they didnt want to relearn all functions changed until I got home. So I am home and when I go into "about phone" in settings and go check for updates it always says the OS is up to date. Even though when I check the version its 4.4.4. Meanwhile all the native apps have updated to their latest verisons. I have already upgraded my phone to 5.0 and today I got my 5.0.1 update today. I get that google doesnt roll out its updates all at once but its been a month since the initial 5.0 update and why is it that I cant upgrade my parents phone and it says its up to date even though its not?
Have you tried downloading the factory image and flashing that over a adb with a USB cable? This will normally nuke everything that was on the phone, but if you change one line in the shell script or batch file which carries out the upgrade (removing the "-w" switch) you can upgrade non-destructively. That's what I have done twice now and it works fine.
Unless your parents are rooted, which sounds unlikely, there are no complications. If they are rooted you have to reroot after the upgrade. But that's not really complicated, and it does mean that you can have an adblock.
I had the same problem two months ago, today I received the update for 5.0.1. Seems that waiting is the only thing you can do if you do not want to get into complications by downloading the factory image and take care of do not wipe your data. The update will eventually arrive, although it can take a decent amount of time.