The delayed launch probably didn't help... but even that (black friday launch) wasn't hyped up or advertised.
To make a splash they should have been having teaser advertisements since the middle of the year and a viral social media campaign in November... and then secure introductory discounts from suppliers to offer a couple hundred items for dirt cheap prices scattered around the different departments with a likit of one per customer... to give them an awesome first experience that will keep them coming back, and rave about it to others (indirect, free marketing).
Maybe Amazon thinks people should know who/what they are and when they are opening... but most people probably don't even know Amazon are open here now.