I said it because it's an option if you can't think of a solution. If you can't trust ppl to keep your seeds safe after you're dead you'll have to tell ppl when you're alive & hope they won't cheat you or else how can they enjoy the crypto you're giving them when you die?
You said don't trust anyone but you also said to tell your family the password or seed while you are still alive. And if you are still alive why should you involve or trust a bank or lawyer because as long as you are still alive everything is still under your control including your family.