Well, camera placement matters in the obvious way: it has to be on the finish "line". Where "line" is really a plane extending vertically from the line drawn on the surface.

I vaguely remember an article about a bike race photo finish that showed that this is not a given and reverse engineered where the camera was pointing (based on background) and who the likely winner was.

edit: found it https://www.tglyn.ch/blog/amstel_gold/