Chrome and Firefox have a context menu entry for printing the selected contents:


However, I am not aware of a WebKit browser that has this feature. Both Safari and Orion function identically as they do not have this feature:


So, in short, this is not a bug but rather a limitation of WebKit as it doesn't currently have this feature. The "Selection" option in the Print Dialogue clearly specifies what it does, i.e. "Select pages from the sidebar". If you'd like to see this added, you're probably better off contacting WebKit developers and asking for this feature. It is worth noting that people have been seeking for workarounds for nearly two decades, e.g. https://macosx.com/threads/print-only-selected-text-from-webpage.299805/