The SRTs were probably produced in a sort of semi-OEM arrangement, in which the buyer got a reduced price in return for taking on responsibility for things like distribution, marketing and service. Sears would've gotten a little sales boost from having the label say AR rather than some home label brand name, but no other AR support. AR would've drop shipped a a year's worth of stock to one delivery point, Sears would've shipped to stores using their distribution chain, the only marketing info would've been in Sears catalogs, and customers with warranty issues would've carted their speakers to their local Sears store rather than contacting AR for free return cartons.
And I wonder whether those military exchanges got them from AR, or from Sears along with Craftsman tools and Kenmore appliances.