Many film scanners capture four channels of exposure data: RGB and infrared. Since developed film can block visible light but is more or less transparent to IR,

Many film scanners capture four channels of exposure data: RGB and infrared. Since developed film can block visible light but is more or less transparent to IR, that winds up being a pretty good map of where all the dust specks are. Which, in turn, allows automatic and very targeted software dust removal that can completely avoid parts of the exposure without dust, producing A quality of output more comparable to that of laborious retouching than inferior automatic software dust removal without a dust map. IMO that alone is sufficient to justify a film scanner over a DSLR.