He was sorry for the birds, especially the small delicate dark terns that were always flying and looking and almost never finding, and he thought, The birds have a harder life than we do except for the robber birds and heavy strong ones. Why did they make birds so delicate and fine as those sea swallows when the ocean can be so cruel?
From "The old man and the sea" by Ernest Hemingway
What does they refer to here? I thought it's natural for this sentence to be expressed in passive form.
And does as here means "like" or "for example"? Or is it a part of so ... as structure? However, Longman says
Do not use so in comparisons without 'not'. Use as: Your handwriting is as bad as mine (NOT so bad as mine).