This is like the president getting sworn in: the thing that gets
the action of the verb is more important than the people
performing the action.
Example: “That treasure lying in its bed of coral, and the corpse of the
commander floating sideways on the bridge, were evoked by historians as an
emblem of the city drowned in memories.” —Gabriel Garcia Márquez, Love
in the Time of Cholera
Here, you could invert the sentence to say “Historians evoked that treasure (and so on).”
But that would take the focus away from that oh-so-intriguing treasure and the corpse. And
since the historians are less important here, the author makes the choice to stress the key
idea of the sentence through the passive voice.