I’m not sure I understand what your question is then. Open source pictures are practically the same thing as Creative Commons. The thing is “open source” means the source is open. Why would you need the source for a picture opened if you’re already freely distributing it? People add licenses to things like code so later people can build upon or take parts of in an orderly way. But if you just wanna share your photo to the world online, you will.
FOSS code explicitly states what it is to not be a nuisance to the creator getting requests to fork/modify accordingly. Most people just rip a picture off the internet and use it. Unless it’s for educational/business purposes where they just want a license as a CYA for them.
Because the only reason people need licensed media are for official projects, whereas those looking for foss/oss code want it specifically for that reason. People still actively look for those licenses when needed, but someone throwing up a photoshopped picture on Facebook doesn’t give a damn what license it has.
If code was shared in more open places (like forums of old) it wouldn’t have a license either even though it is technically foss until stated otherwise. That last bit is the gotcha and reason why those looking to legally cover their ass seek out these licenses for commercial/educational purposes but only care about open source software personally due to the hope it’s easier to find exploits in the code (or any other reason).