Position of Oregon vs Europe on a Flath Earth Map
When it is day in Europe, it is night in Oregon US.
Map by Gelason, 1892
It is even MORE pronounced because of the shape of the "flat" earth... which also prevents the sunlight from casting across the north pole.
Map by Orlando Ferguson, 1893
Diffusion because of dirty air also prevents sunlight from being cast across the entire earth; it has a vanishing point.
Also, occlusion from clouds and mountains and trees, at huge distances these things play a role as well.