Media files are not stored in the RM database. Rather, RM stores a pointer to media files. The pointer consists of the complete Windows file string, starting with the drive letter, including all the subfolders in the file path, and ending with the file name itself. I'm a PC user, and I don't know what the file strings look like on a Mac.
Having been linked into the RM database in this fashion, media files may be linked to a wide variety of objects in RM - people, families, events (also known as facts), master sources, source details, places, place Details, and names. RM doesn't really support names as free standing objects separate from persons as does FTM. Rather, it supports alternate names in addition to the name which is associated directly with a person, and it is these alternate names to which media files can be linked.
For the most part, the linking of media files to objects can be accomplished in two different directions. You can start with the object such as an event and do an Add Media where you choose a media file to add, or you can start with a media file and do a Tag Media where you choose an object such as an event to which the media file is to be tagged.
Your question arises because a media file can be linked either to an event (or person) or to a citation for that event (or person), or to both, if you wish. Users debate on these forums all the time which is the better way to do it. The camera column in the Edit Person screen is telling you about media that is linked directly to the event (or person). Media can be linked directly to an event (or person) whether or not there is a citation for the event (or person). It's easy to see if there is media linked directly to an event (or person) because either there is or there is not a green check mark in the column under the camera icon. And if you click on the green check mark, the list of one or more media items for the event (or person) is readily accessible to you. For that reason, many users prefer to link media to events (or people) rather than to citations.
By contrast, I think a citation is a much more logical place to link media files that are really source documents such as census records rather than being photographs of the individual. And if you memorize and past citations in multiple places, then the tags for any media files linked to the citation are memorized and pasted along with the rest of the citation. The disadvantage is that there is no indication whatsoever on the Edit Person screen as to whether or not your citations have any linked media or not. And indeed, even after you click the green check mark in the column for your citations, you see the list of citations but there is still no indication as to whether any of the citations have any linked media or not. And it's even worse than that. Even you highlight and edit one of the citations, you still don't see any indication as to whether the citation you are editing has any linked media or not. It's only after clicking the media tab as a part of editing the citation that you can see whether there is any linked media or not.
Despite this horrible design of the user interface, I still link my media files to the citation rather than to the event (or person) because it's the logical thing to do and because it's just the right thing to do. I have this naive hope that the user interface for media linked to citations will be improved someday. In the meantime, I either do a lot of clicking to get to media linked to citations while cursing under my breath, or else I use SQLite reports of my own design to help me manage media that is linked to citations.
I'm certainly not advocating that my approach is the best for everybody. My sense is that most users link media to events (or people) rather than using the approach I use, simply because of the way the user interface works. So make your own choice on what works best for you. Link your media files directly to events and people. Or link your media files to citations for events and people. Or do both.
The following is only a guess, but I do have a guess as to why the user interface has not been changed. For a very long time in the history of RM and its predecessor Family Origins, it was possible to link media in only one direction - namely, start with an object such as a fact or a person and link the media file to the object. The ability to start with a media file and tag the file to an object is a relatively recent addition to RM. If you start with a media file, it's about as easy to tag the media file to a citation as it is to link a media file to an event or person, and vice versa. And it's easy to see all the places a media file had been tagged. So I think this tagging mechanism was viewed by the developers as a solution to the problem of how deeply buried in clicks media files are when they are linked to citations. But I don't think that view accurately reflects how users really work and how badly they need to see media files from the Edit Person screen.
This message is already too long, but I need to end by pointing out that as an extreme source splitter I really link my media files to Master Sources rather than to Source Details (that is, to citations). Doing so makes a minor difference when I first link in the media files to my sources, but it makes no difference at all from the Edit Person screen. After you click down from the Edit Person screen to where you can see media files that are linked to citations, the media files linked to the Master Source and the media files linked to the Source Details are displayed on the same screen.