Can someone explain how a company can claim the uploader gave them a license to an image when they do nothing to check if the person uploading the image had own

Can someone explain how a company can claim the uploader gave them a license to an image when they do nothing to check if the person uploading the image had ownership in the first place? I have seen plenty of examples of people using the FaceApp on famous people with some image that the uploader clearly doesn't own. Furthermore, don't people have rights over their likeness that overruled certain rights the copyright holder has over the image? For example, I would own the copyright if I met some celebrity on the street and took their photo. That doesn't mean I can freely use that image in my advertising.