As a large corporation with a widely recognized brand, your desire is to have everything associated with your brand consistent right down to the last detail. A uniform presentment of your product is critical in creating a professional look which attracts potential customers as well as retaining current consumers of your product.
There are two main factors that contribute to this insidious effect. The first is a subjective understanding of photography, meaning that each specific vendor has their own concept of photography and photo editing and how a photo "should look", completely inconsiderate of the overall intended effect of the corporation.
The second factor is equipment. Inadequate and incongruent equipment among multiple vendors for example: outdated single frame cameras; different types of lighting; diverse image backgrounds; various monitor color calibrations; even contrasting brands of cameras can cause differentiation, for instance the current top brands in digital cameras the Nikon D850 produces a softer color than the Canon EOS 5D Mark IV.