By default, KIO creates Places panels entries only for Home, Network, Root and Trash: https://cgit.kde.org/kio.git/tree/src/filewidgets/kfileplacesmodel.cpp?id=7eb6333bdb48f39d592b07c565eb8a7d02cbf0d3#n130 This is a little sparse. We should include in the default set some more important locations in the user's home directory: Downloads, Documents, Pictures, and Music. Movies is a maybe (I don't know how many people really have local video collections in their home folders anymore in 2018).
Patch available: https://phabricator.kde.org/D10245
*** This bug has been marked as a duplicate of bug 203472 ***