Copyright is simple and straight forward. If you want to use a photo you need to get written permission, usually in the form of a licence that you pay for (see these examples at my portfolio). The only exception is photography not under Copyright licence, but Creative Commons. It really is that simple. Almost all countries (including the US) have signed to international treaties (see Wikipedia) and so have agreed to protecting the rights of creators and the creators’ choices. Me, I also need the money. Photography is not a free / cheap game to play (see why, here).
The US has muddied the waters in two ways, firstly by creating a copyright office that requires US based creators to register their works so that they can get full damages awarded. No other country has this requirement, but the US tries to impose this on all creators, US-based or not. The only benefit I see of this system is that the US gets money from international creators, and hopes to profit from the fear of US-based infringement. The second way the US has muddied the waters is by not teaching their children in education enough about copyright and what is considered infringement, so ignorance and this lax culture has permeated on the internet. However, this second problem is not a US exclusive problem. There are reports on websites like Photo Attorney of India based website designers and creators building websites for US owners, only for the US owners to be (successfully) sued for copyright infringement. If you own the website, you approved of all of the content and so are legally liable for all infringements (see point 1 on this page of the Photo Attorney website).
In any case, there are now lots of websites that describe the “myths of copyright” and the common excuses violators make. Of most pertinent to me, as I’ve seen this a lot recently on social media is the notion that it’s ok to use someone else’s photo on your website, provided you link it back to the original source. I was livid when I saw some leech using my photos without paying me. I already have an agent and his lawyer pursuing a case of this; refer to point 9 of this Photo Attorney document: http://www.photoattorney.com/wp-content/uploads/2013/02/Excuses-excuses.pdf. Also, PetaPixel recently did a great article that is pretty current, and in the same vein at the Photo Attorney list, just because you put my name there DOESN’T give you licence to use my photo without paying for it: http://petapixel.com/2013/08/03/10-bogus-excuses-people-use-when-they-steal-photos-from-the-web/.
For some strange reason, the most commonly violated photos of mine are my sumo images. I dare you to steal them… my lawyer needs a new spa on his back porch and I’m dying for a new Sony a99. 😉