Because Tesla says that it is a rendering of what the car thinks it is seeing, meaning that the rendering is supposed to roughly correlate with the information

Because Tesla says that it is a rendering of what the car thinks it is seeing, meaning that the rendering is supposed to roughly correlate with the information upon which the FSD systems are acting. In contrast, the animations of a car battery being charged don't claim to be realistic in any sense, and they deliberately attempt not to be realistic: oversized images of batteries or other standardized iconography, stylized arrows or other indicators of charging "flow", etc.