I'll echo what has already been said regarding the sheer number of B&W speakers out there in the wild. It has to be orders of magnitude more than almost any other high end brand.
Adding to that, they are sold by some of the more mass market chains like Best Buy via their Magnolia HiFi locations (which nowadays is usually just a section inside the store rather than a dedicated separate location). Last time I was in my local Best Buy the Magnolia section had Martin Logan, KEF, Definitive Tech, and B&W. The latter seemed to have the largest share of displays and marketing within that area. And as far as I remember they have always featured B&W, while some of those others feel like more recent additions.
It's easy for us forum users to think that Sonus Faber, Focal, B&W, Totem, Dynaudio, etc are all very well known and widely distributed. But I would guess that most "normal" people will know the B&W name before any of those others, by a wide margin.