If they don't want it hotlinked, the web designer can make it so it doesn't.
Usually that doesn't stop copying and pasting the URL, but it will prevent image hotlinking (and is amusing because for the person doing the linking, the image is still cached so they have no idea that everyone else is seeing the "stop being a cheap *******" gif that the originating website has set up for hotlinks.
At the same token, the idea of "if it's online it's fair game" is flawed, because that will only encourage people to not put things online. And then where would you be? Sad and unable to view images, that's where.
Personally I find it strange that people would put up a picture because (presumably) they want everyone to see it and then complain that their bandwidth is being taken up by people viewing it.
If I link to a picture on a site, I am linking to the picture and not downloading it to use myself. In effect, I am keeping to copyright laws by not stealing the picture and putting it on Imageshack or whatever. Anyone who complains about that should stay away from anything considered public domain like the internet. It's like putting a picture on your shop window in the high street and then complaining that people are stopping to look at it and causing congestion on the sidewalk.
If I see a funny or relevant picture on your site, the link I put is still to your site. If anyone viewing becomes interested, they can erase the tree and load the index page of your site. If you are selling stuff, you got a free advert for your site from me, what's your problem? If you are really paranoid, you can always put a discrete url on the picture so anyone viewing it will see where it's from.