Don’t those cases establish that police may, within the bounds of the fourth amendment, detain both the driver and any passengers; which then triggers requirements under other state laws allowing police to compel detained people to identify themselves?

E.g., https://en.wikipedia.org/wiki/Stop_and_identify_statutes ?

As that link indicates, not every state has such a thing. States can; not every state does.

(And "identify" isn't necessarily the same as "show ID". It's legal to not have any form of ID in the US whatsoever - this comes up with voter ID discussion a lot - and those folks are still allowed to ride in a car.)

It gets even weirder because at least in same states it is ruled if a crime has an age component then once again you can't be forced to reveal ID (which would betray your age) and incriminate yourself even if driving. And then in some states you're required to answer questions unrelated to your identity like if you're carrying a weapon (unless you can't have weapons, in which case you'd be incriminating yourself and then again you don't have to answer).

Not legal advice.