Electropolishing selectively removes microscopic high points or peaks much faster than the corresponding rate of attack on the corresponding micro-depressions or valleys.
As a result, the surface of the metal is microscopically featureless, with not even the smallest speck of a torn surface remaining.
During the process, a film of varying thickness covers the surfaces of the metal. This film is thickest over microdepressions and thinnest over microprojections.
Electrical resistance is at a minimum wherever the film is thinnest, resulting in the greatest rate of metallic dissolution. The basic metal surface is subsequently revealed bright, clean and microscopically smooth.
In summary, electropolishing removes metal. It does not move it or wipe it. The basic metal surface is subsequently revealed -- bright, clean and microscopically smooth.
By contrast, even very fine mechanically finished surfaces will show smears and other directionally oriented patterns or effects.