Why do multiple people operate one camera in Hawthorn Tree Love?

Hawthorn Tree Love uses multiple people to operate one camera, which is a depth montage shooting technique. Characters are at different levels, and things near and far have different scales, so a scene-setting mirror must be used to coordinate. Therefore, the "photographic nature" still needs to be interfered by people. In fact, long shots just use scene and camera scheduling instead of montage combination to achieve the replacement of the scope and content of the picture. So some people call this technique "montage inside the lens" or "depth montage".