i'd argue that this is still an education issue.
Discussion
I dont think its just a skill issue. The spec on BIP39 passphrases is really loose. There is no standard length max or character set. Passphrase input on a hardware wallets is usually tedious and feels like an afterthought. It needlessly increases complexity in an heir recovery scenario, and there is no standard descriptor to indicate that there is a passphrase in play.
That's still an issue of them not understanding what they did when they applied a passphrase all those years ago. If there was more education, which I feel that I've seen now on some wallets, then this person might have struggled as much.
The problem is that in a posthumous recovery scenario, the surbiving heirs have no standard to help them understand that the seed needs a 25th word. The person that has to remember that they set up a passphrase is dead.
Perhaps then the owner would need to educate the heir on how their wealth is stored.
