Things like kids (declared at birth), significant others (declared at weddings), buying houses (declared during the purchase), etc, are all known to the state and taken into account. Pretty easy in most cases.
I don't think there's much possibility to hack the system since to only option you have is to agree or not. And if not I guess you need to file manually.
Designing a hermetic container that lasts for years is non-trivial
Huh ? My cheap plastic watch is hermetic to 4 atm, and for years. Plenty of things are. And for a HD you don't have to stand more than 1/3 atm of pressure differential, something trivial. Having used hard drives at high altitude and seen them die quickly, I always wondered why they don't simply seal the damn things with air at 1 atm inside.