[dTal]

Do you think that's an effective deterrent? Do people go "better not download that inappropriately underage video, they might not let me in the library anymore"? And, if a punishment is not an effective deterrent - what's the point of it? What are we trying to achieve?

Going meta - your comments are all along the lines of crime and punishment and whether they "deserve" it etc. The replies to you are all along pragmatic lines - what we should do to make society behave the way we want. These approaches are incompatible - when the pragmatic approach disagrees with the fire-and-brimstone approach, ignoring pragmatism will by definition get a worse outcome. Your own feeling of righteous anger is not a good thing to optimize society around.

The notion of justice and punishment is a subsidiary mechanism to pragmatism - one of many ways to achieve a peaceful, stable society.

(One that does not appear to scale especially well beyond groups where everyone knows each other, or into deeply complicated and partially enforced rule sets. Don't kill your tribe member or the tribe will cast you out = effective. Don't exceed the speed limit or you might possibly receive a fine of some constant amount plus a proportional factor to the amount you exceeded it by = ineffective.)