Copyright law is not more difficult or convoluted that other law. Is is just that it isimpossible (in all laws not just copyright law) to cover every conceivable case into tiniest detail. Therefore it is unavoidable to use sense of proportions and common sense. That is what the courts do. Most people understand that it is neither practical or even desirable to credit every photographer in a photo manipulation composition, the effect would be that of ridicule -the opposite of what is wanted. But there will always be rigid and inflexible people in the world, it is called "paragrafrytteri, swedish for "pettyfoggery".
I understand your reaction but don't despair. Jupiterimages and photo.com's preposterousclaims can never be made to hold in reality.