The default behaviour in recent versions of OS X is to only display the scrollbar in certain circumstances based on the connected devices and what you are doing. For example, scrollbars are always visible when my USB mouse is connected, but are hidden when it's disconnected and I can only use the trackpad. In your screenshots, each column is quite short and no scrolling is possible, so the visible scrollbar just manifests as a thicker separator rather than a usable scrollbar.
You can change this behaviour in the General pane of System Preferences. The "Show scroll bars" option defaults to "Automatically based on mouse or trackpad" but can be set to always hide (except when scrolling) or always show.