I'm not entirely sure I agree that Facebook is in the right here - analyzing the ads that are shown to you is different from downloading photos you uploaded.
However, your principle argument that there's a difference between Facebook serving pictures to friends and massive, automated serving of pictures to bots and scrapers. I understand that there's no good way to differentiate, and that the bits that are sent over the network are the same regardless of who is consuming them, and that my friends have the technical capability to upload the images elsewhere.
But just as you get different outcomes between one situation with an individual policeman watching traffic, pulling over reckless vehicles or tailing a suspect vehicle with a known license plate and another compared to a network of automated license-plate readers and speed cameras tracking the city-wide movement of lawful and criminal people alike, you get different outcomes when you differentiate between bots and live users.
However, your principle argument that there's a difference between Facebook serving pictures to friends and massive, automated serving of pictures to bots and scrapers. I understand that there's no good way to differentiate, and that the bits that are sent over the network are the same regardless of who is consuming them, and that my friends have the technical capability to upload the images elsewhere.
But just as you get different outcomes between one situation with an individual policeman watching traffic, pulling over reckless vehicles or tailing a suspect vehicle with a known license plate and another compared to a network of automated license-plate readers and speed cameras tracking the city-wide movement of lawful and criminal people alike, you get different outcomes when you differentiate between bots and live users.