"this whois record shows it expired on Dec. 13, suggesting someone forgot to renew its registration. Naughty, naughty."

I have several domain names registered (I have a few hobbies - anime, dollfies, etc - and these DN all point to the one machine serving various web-sites for said hobbies) and the registrar I use allows me to tick a "automatic registration" box for each of these domains. And just to make sure I don't forget about them, it still sends me a reminder every year that domains X, Y and Z are about to re-register.

So why is this sh*t still happening?

Stop banging your head against the wall and update your DNS administrative contacts to someone who is there.

Yes I relied on auto renewals too.

nearly lost a domain because the domain registrar had the wrong date for some reason in their database compared to the actual registrar.

Even then there have been lots of documented cases of auto renewals not working, you are still relying on one companies system to do the job, if it fails for any reason you are screwed, and relying on emails getting through from a registrar is also flawed as its easy for them to suddenly get eaten by a spam filter and has been seen to fail numerous times as documented on the reg from time to time.

My answer - all domains with one registrar, auto renewals on and I log on once every six months or so and renew anything which is going to expire within the next few months and I keep an eye on the renewal dates (especially when I do transfers as that appears to be where the dates can go wrong).

End of the day things go wrong. What is wrong here is the design of the system such that it had a single point of failure and lack of monitoring of their domains.