Those are things that when you forget them, you can take steps to re-learn them, because the information is publicly available.

On the other hand, I am absolutely certain that I have truecrypt volumes on old backup drives somewhere that I haven't the foggiest idea what the corresponding passphrase is anymore.

The former things are all public information, meant to serve a public function. Personal passwords are not that. Going to jail for forgetting, is like going to jail for losing a physical key - not even a key for an important public function, but anyone's key that was used for any personal purpose.

One could assert that legally you will be punished for this, like the UK have done here, but it's quite a barbaric thing to do without any precedent even in historic infamously-authoritarian regimes.

Road signs is bogus. People sign up for extra responsibilities via the licensing process.

The tax one is a little more interesting, you don't have to file if you don't make any money. If you make more, the payer is supposed to report as well.

Everything i can think of, where you're compelled to do something, there's at least one other person involved.

Your two examples are rules that are public information, and forgetting them can indeed have legal consequences.

A password is a piece of private information, and requiring people to remember stuff they generate in their own head seems just a tad draconian.