Prohibited to stop and park: “[…] 10 metres before the pedestrian crossing […] Note that the prohibition does not apply after the pedestrian crossing” (Driving Licence Book, 19th Edition, page 70).
Before pedestrian crossing
You cannot see the red area. When a pedestrian leaves the red area, the margin is basically non-existent, which means you hardly have time to react before an accident happens.
After pedestrian crossing
Visibility is still obstructed in the red area, but the main difference is that you have a much greater margin to notice the pedestrian.
But would not it be safest to prohibit stopping and parking both before and after?
– Yes, but practical considerations must also be made. In cities, there is often a lack of space, and a prohibition after the crossing would mean that many parking spaces would disappear. Compare this to the speed limits; highways would be much safer if the speed limit was 30 km/h, but that would not be practical.
More examples of explanations: