Then you aren't comparing like-for-like. Value in bitcoin represents a disagreement with your consideration of who is "good", in the same way investment in a currency might be seen as confidence in the institutions that back it. You could just as well argue there should only be one monetary currency.

How much effort do credit-rating, fraud etc agencies make? A centralized currency requires trust, which crypto-currencies don't. To compare value, you need to add a price tag to this liability. The lower cost comes from the savings made in not having to secure against the central authority itself.