There's no way he would have been privy to Casterly Rock's expired gold mines, Cersei's debt to the Iron Bank, or Euron's supernatural ability to rebuild a fleet. Uneven access to information has long been a tenet in the series and is a big reason why Martin's POV writing style is so effective.

It's easy to use a general blanket statement to support your position but it falls apart when the actual context is considered.