[conan50]

It probably is a bit of a shock that Amazon treats docs like the red-headed step-children on their tablets. But I also think that compared to their e-ink readers they know the tabs will be used in offices and such and there is a legitimate need to have the documents (books and docs we upload to Amazon or side load) separate for that reason. Nevertheless, my personal docs/books do show up in my collections even though they don't look as pretty without their covers. I don't think Amazon is being nefarious, just like their ereaders don't have encryption and their tabs do, it is covering different use cases.
BTW if it troubles you I would contact Amazon and complain. They actually do listen to their customers. Years ago I requested that they add night mode to their reading background choices, and we have that. I also suggested years ago that Amazon put out their own video streaming device. Man they should be paying me for these ideas :-)