It does make you wonder how they managed to get their internet set up and running in the first place (scratches head in puzzlement) and for those who didn't know who their ISP was, who is paying the bills?
This is really an indication of how reliable computer technology has become. Like you, I come across lots of people who haven't a clue when it comes to router passwords - not only home users, either.
I know of at least one solicitor's office where nobody knew where the router was, and when I found it nobody knew what the admin password was,or the SSID, or anything at all about it. The broadband connection had been working flawlessly for so long that they all took it for granted.
Back in the early days of Wireless home networks it was quite an ordeal to set up a router supplied by the ISP and many only had WEP encryption. PCW used to charge £50 to do it for you and believe me they had plenty taking them up!
Nowadays it's almost too simple - plug'n'play as it were. The problem is that people just don't look at the whole picture anymore as long as it works! I can go to troubleshoot a wireless router and when you scan what's available there's usually 3 Sky routers or Virgin Routers to choose from. Do you think the users actually know which one is theirs? They don't even know that it's probably on the bottom of the router with the Encryption key - the number of times they have been trying to connect to the wrong one is unbelievable.
Most don't realise that a simple reboot of the router will cure the problem and with Virgin Routers the default password to access the router is "changeme" ...... which I do!
I secure my home network by not broadcasting SSID, WPA encryption and locked to specific MAC addresses. It is this last one that very few people know about when talking to others about netword security.