One reason super singles are popular on cement and trash trucks is they provide more floatation over soft ground. Another is that there is no accumulation of debris between the tires that will be expelled when getting back on paved roads.
Super singles are far more popular in the southern states than where the snow flies. While they may get better mileage their profile also doesn't lend itself to slick and/or snow covered roads.
I do business with a local tire company that services several concrete companies in the area. Nearly every time I've been at their shop I've seen cement truck tires coming in from the field. Almost every tire that had a problem while on the road also required the rim to be replaced.
The same also often happens for tires in dual configuration. The big difference is the cost of a super single tire and rim compared to those used in dual configuration.