"Has to be displayed both forward and aft." Where are you then going to put such lights where superstructure is not in the way? Not all ships have a raised mast both fore and aft. You find from looking at illustrations that the lights must look a certain way from a certain aspect. Yes, they must be visible from all aspects, but their pattern...one light higher than another, one forward of another, different colors above or fore/aft of another, etc....varies with aspect. Bow or stern on looks one way, from the sides another.

Some illustrations:

https://handbook.safetransport.vic.gov.au/boating-rules/navigation-lights/vessel-navigation-lights-to-be-displayed/

https://www.facebook.com/story.php?story_fbid=734154765822931&id=onlinethirdmate&seo_visit=1

https://astrolabesailing.com/2015/02/09/colregs-lights-sailing-at-night/

You can find "a million" of these things with a quick search just with the term-->anchor lights. I did (and honestly, at a glance, they don't all look so very uniform to me...)