The question, therefore, is can we find any entities (governments,
institutions, individuals, etc.) that are trust-worthy enough.
I think we can find many entities that are trust-worthy enough for
some purposes; I doubt we shall find any entity that is trust-worthy
enough for all or even most pruposes. That is why I don't believe
in a global single-rooted PKI.
As long as people still choose who to trust based on their assessment
of risk for that particular situation, I have no problem with the
government being one of the parties that is able to make assertions
about someone's identity. However one of the pitfalls associated with
the government acting as a CA is that the government can compel you
to place trust in its credentials even when the trust is unwarranted.
Keith