I don't think the dollar analogy is very useful. The kind of trust
we place in money is a very specific kind of trust, and the risk
we take in trusting money is generally limited to the denomination
of the note or coin. This is so well-understood that most of us
never think about it - though we may realize it's prudent to
examine a $100 bill more closely than we would a $1 bill before
accepting it as valid.
OTOH, the appropriate kind and degree of trust to place in a
domain name or CA for a domain name is not well-understood,
even though it may be implicit.
Keith