Three reasons that I can think of: 1. These images are likely captured on large-format glass plates, not tiny sensors. Therefore, the amount of magnification

Three reasons that I can think of: 1. These images are likely captured on large-format glass plates, not tiny sensors. Therefore, the amount of magnification required is much less (these may be nearly 1:1 on a standard laptop display). 2. Chemical emulsions typically have much more dynamic range than digital sensors, allowing for more highlight and shadow detail. 3. Capturing colors in three separate exposures gets rid of the need for de-mosaicing.