One could definitely argue that because Apple controlled essentially all of elements of artistic expression (lighting, position of the camera, position of the subject within the frame, iso, shutter speed...) that make a photograph unique and McDonald's program was more or less a timer, Apple is the rightful owner of the copyrights in the images.
Your statement that they are free to do what they wish is not accurate.
Use of someone's likeness without their consent could result in an appropriation claim. That's why, when you watch reality tv shows, people who don't sign waivers and releases are blurred out.
A defense to the claim of appropriation is consent, whoever, these individuals were on private property and did not expressly consent to be a part of Mr. Kyle McDonald's project. With respect to implied consent, I'm not sure a judge would side with McDonald if an individual brought a claim. Because the mall and the Apple Store are private property and McDonald did not himself have consent to photograph, the individuals photographed may not have had the requisite authority to consent (implied or otherwise) to be photographed by McDonald.