I was convinced that Voronoi polygons were created so that each location in a polygon is closer to the origin point present in that polygon than to any other seeds
In Snow's famous case study in Soho, London (see screenshot), when I compare the Voronoi partitioning to the distances to the nearest point, I realize that some deaths (red figures) are in the polygon of a pump (white figure) while they are closer to another pump.
How can this be explained?
Map projection is EPSG 3857 (WGS84). Reprojection to British national grid gives me the same result.