The wording of this achievements is a bit confusing. The requirement for this to unlock is to have at least 5000 of every building on Earth.
The last building to get up to this number will probably be Newspapers, and it will be very very late-game (i.e. two more soft resets and you will complete the game). I had around 620 of the 633 possible unlocks completed when I reached 5000 Newspapers, unlocking the achievement.