I think for the US, they should ensure tzdata contains at least one city for every state. That’s what they do for Australia. Now, it so happens their current rules-only add city if in recent decades it had distinct time zone rules-happen to produce that outcome for Australia, because in Australia time is a state issue and historically every state decided for itself whether to have daylight savings and when to begin/end it. Still, I think they should amend their rules to say “capital and/or largest city for every first-level subdivision of major countries”, given some reasonably objective definition of “major” (e.g. G20 nations)