I disagree that that is the problem. There are many ways to sell photos online, but a photo editor doesn't want to be restricted to only browsing a pool such as Getty or Shutterstock (which are not open to all comers either). My argument is that while there are widely accepted mechanisms for establishing copyright status (eg CC-by-SA or sharealike) there's no universal standard to automate or streamline licensing, which is why (rent-seeking) brokerages persist.It's a shortcoming of the Creative commons approach that it doesn't include any sort of transaction mechanism for the CC-BY version. I went to Dan Catt's Flickr page; there's a statement of copyright but there's no link to buy a license for the photo. This is the problem.

Licensing is a pain in the ass because it's not automated; it's not automated because many artists are scared of pricing (and I say this as an artist). They're reluctant to stick a price tag on their work out of the fear that they'll pick one that's too low or too high and as a result there's no standardized way to license a an interesting piece of art you stumble across, other than by contacting the apparent copyright holder and trying to enter into negotiations, which is so time-consuming that it's often not economically efficient for the would-be licensee. It's cheaper to assume the business risk of occasionally infringing than to license IP without any standardized framework for doing so - especially for articles of this kind that are thrown together in the space of an hour or two. A URL is not helpful because (as with this example) we have no idea whether it will provide a mechanism to perform a license transaction or not.

What I'm proposing is adding term metadata that allow the information about pricing to travel with the picture like any other piece of metadata. It's kind of ridiculous to have all sorts of metadata codifying the creator/copyright owners ownership interest in the IP but not to include any on what that interest is valued at. If such term metadata were to become standardized in similar fashion to the Creative Commons licensing, then artists would be able to sell more of their work with less transaction overhead, while licensees would be able to buy with the same convenience that consumers enjoy.