>The big political parties spend literally half a billion dollars a year on advertising. If they find a photo good enough to go on the front page of their website, they are perfectly willing to make that photographer's year, and they're not going to skimp on something that important.
I'm actually surprised that a major campaign would just see a CC photo on flickr and decide to use it (assuming that's what happened). Pretty much no ad agency or other non-editorial user would do such a thing. There's too much risk that the photographer could object to the use (in spite of the CC licensing) or didn't actually own the rights to the image in question or had exclusively licensed it to someone. As someone else pointed out, they're not even using the image in a way that technically meets the letter of all the CC license requirements.
Political campaigns are ephemeral organizations and take financial and legal risks at a far higher rate than a typical company.
They get no credit for being good with money, only for winning the election. If they lose, they just disband and there is no one to sue. If they win, they have a good platform to find people willing to forgive or fund debt payments and legal settlements.
I'm actually surprised that a major campaign would just see a CC photo on flickr and decide to use it (assuming that's what happened). Pretty much no ad agency or other non-editorial user would do such a thing. There's too much risk that the photographer could object to the use (in spite of the CC licensing) or didn't actually own the rights to the image in question or had exclusively licensed it to someone. As someone else pointed out, they're not even using the image in a way that technically meets the letter of all the CC license requirements.