Images are deleted fairly efficiently, if they are not then you get an out of control situation very quickly. Thousands of bad images get uploaded every week, there is simply no way to give each one 20 minutes of editor time to review. This one was deleted because it claimed to be fair use, but didn't link to any article. That may seem extreme, but when we are dealing with thousands of images the work really has to rely on the uploader.
Every effort is made to educate people as they are uploading, and including fair use images isn't super easy, but some people argue that it shouldn't be since we are a free encyclopedia.
Probably no more time can ever be spent per problem image, as we are rate limited by number of volunteers, but better upload tools, and/or better education about the policies would be a big help I think.