This is a confusing case even for non "low-tech" users. I had a shared dropbox folder with a friend. I was done with my copy of the files, so I deleted them because I was close to my dropbox space limit. He freaked out because dropbox then deleted them from his drive too. In retrospect, I guess it makes sense, but the idea that a delete would propagate was certainly not the expected behavior.
If Dropbox synchronizes folders, including edits made to files, why wouldn't it synchronize a delete? If the expected behavior would be that it propagates anything but a deletion, that would be truly bizarre and confusing wouldn't it?
Sure. It makes absolute sense, but it wasn't the behavior either of us expected. You could easily, and rightfully, say that our expectations were wrong and inconsistent. I deal with frustratingly inconsistent customer expectations all the time, so I sympathize when I'm on the other side of the table. Just an anecdote point.
Edit: To be more clear, I expected the behavior that SVN gives me, which is that a change is pending to commit by default, but an add or delete isn't. I have no good explanation for why I expected dropbox to behavior like SVN.
Unlike high-tech users, low-tech users end up permanently scarred. They are also afraid of looking dumb, which compounds the problem. Dropbox has incurred significant, if hidden, usability debt.
