What is the benefit of using laser scanning vs. Photogrammetry “image-stitching” that most 3D-Scan-Apps are using?

One Word: Precision.

Photogrammetry (aka “Image-Stitching”) relies on 100+ photos taken of the object you wish to model. It does not require or have a depth sensor. The algorithm then tries to identify “features” that allows it to derive the camera position from each image.

Due to the very limited accuracy Photogrammetry is mostly used in large scale scans for outdoor applications such as geoscience, surveying, and historical architecture. It is a good fit if you do not require great accuracy and are relying on “texture” to give you the sensation of structure.

The latest iPhones have a true TOF 3D LiDAR scanner (depth) built in . Its precision is much lower than laser scans (about 1 to 10 cm).