At the time, most landscape photography was done using the dry collodion process, which required exposure times of about 15 minutes. (Wet collodion exposures required substantially less time, around 30 seconds, but had to be developed within 10 minutes. Hence, it was most practical for studio photography — most landscape photography was done using the dry method).

At that exposure length, moving objects like carriages and pedestrians don’t show up on the final exposure; they don’t “register,” so to speak. They’d have to be stationary for most of the exposure time to even show up as a “ghost” image.

In 1880, the collodion processes were replaced with gelatin plates, which reduced exposure times greatly, and that’s when you start seeing people and vehicles showing up in the panoramics!