> Even if a luser can roughly guess what $ts means, it's never going to make it into the UI.
It's not intended to. It's designed for standardized machine-to-machine communication, which is currently a mostly unsolved problem for zoned timestamps.
Human readability does not mean end user readability. It's good if humans can read it so that programmers/admins can read it, and also end users if they happen to be exposed to it. But for display to end users, it should always be formatted in a localized, naturally readable manner with no concern for machine parsing (which is what the second quote is referring to).
It's not intended to. It's designed for standardized machine-to-machine communication, which is currently a mostly unsolved problem for zoned timestamps.