Why do far away objects appear to move slowly in comparison to nearby objects?

It's because the angle under which a certain distance appears to you depends on how far away the object you are looking at is. I mada a diagram: One object is far away, one object is close. Traveling by the same distance, you see a large angle for the closer object and a small angle for the far object.Thus the angle grows slower for far away objects and thus it seems that you travel more slowly with respect to them.