Having used Google Chrome for a long time, I've previously taken it for granted that multiple tabs in a given browser window can be selected, either one at a time (Ctrl-click) or in a contiguous range (Shift-click). (The main reason one would do this is to drag multiple tabs simultaneously to a new browser window, or from one window to another.) I'm giving Mac Safari a chance to win me over, but the very basic functionality of selecting multiple tabs appears to be completely absent. Am I missing something?
Having never needed or even thought to do this I see the behavior you are talking about. And I believe the Safari engineers may have been of a similar mind.
I see no combination of keys that will allow you to select multiple tabs, so I am thinking that may not be possible out of the box with Safari.
That does not mean that there is not an extension (Plug-in, in Firefox lingo) that might provide that functionality but I am unaware of any that do this. You may be out of luck.
Starting with Safari 17, which is installed by default on macOS 14 Sonoma but also available (via Software Update) for macOS 13 Ventura and macOS 12 Monterey,[cite] Safari supports selecting multiple tabs! Hold shift and click to select a continuous range from the current tab to the clicked one, or hold command and click to add or remove individual tabs to/from the selection.
These behave all the usual ways: you can close multiple tabs, reorder them within the same window, move them to different windows, move them to a Tab Group in the sidebar, and so on.