If you don't provide a photo through ERAS, the program will probably take one during your visit.
This is an interesting thought. I'm not sure it's legal to do so without written permission, although I guess simply showing up for an interview might give me implicit permission for a photo. In any case, I don't do this.
I've also heard they can't SEE your photo until after they've decided to interview you, anyway...
So, this turns out to be complicated. Several years ago, this was the way ERAS worked. All of the photos were screened out until you checked off "invited for interview" at which point you could see the photo. Of course, you could completely bypass this by chcking the box, looking at the photo, and then unchecking the box.
Now, things have changed:
1. I can screen all photos, so I can't see any of them. Or they are all visible. There is no middle ground.
2. Applicants can decline to upload a photo and await for an interview decision. Once a decision is made, they can then upload the image.
Theoretically, this is the best combination, since it allows complete control on the applicant end, with reasonable control on the program end.
Demanding a photo for a complete application would seem to have some legal risk associated with it -- applicant could argue they were rejected because of their appearance. But, if you send me a pic of yourself dressed as a slob in pajamas, I assume I could reject you for that alone?