Leaving aside the problem of single-issue parties, the point remains that if radical transparency were a vote-winner it would get implemented. But it's not a vote-winner because people don't want it; not only does no political party advocate it, but there's no grassroots movement calling for diplomatic communiques and tax returns to be made public. It's just not an idea which anyone takes seriously or wants.
People care about their local school. Their rubbish being collected. Their job being secure.
Abstract stuff like radical transparency is too complicated a platform to run on and not only that it's a single issue that can't win votes.
That's why democracy's pretty weak compared to an altruistic dictatorship. But better than any other form of realistic government out there.