But since you brought it up, how much money could they have paid to make you not feel like they're exploiting the homeless? You could have everyone read and sign complicated legalese consent forms and really just end up not giving a bunch of homeless people some money.
edit: Presumably this is happening on public property, so they have a right to take people's pictures anyway. I don't know what the laws are regarding rights to use people's "likenesses" the way many entertainment venues tell you they can, but I'd expect using it for model training is going to have a pretty low bar. If they weren't lying they're paying someone to look at a camera for 5 seconds. Hell, I'd agree to that and I'm not even concerned about how I'm going to pay for my dinner tonight.
Just because it's difficult to identify the harms caused by someone stealing your biometric data that doesn't mean there are no harms. Gaining access to someone's biometric data clearly opens them up to certain types of risks ranging from identify theft to surveillance. Fraudulently gaining access to someone's biometric data is wrong even if the data is never abused or exploited.
That informed consent should be obtained seems obvious -- perhaps some of those people wouldn't want their faces to be used in that way. Are their desires without meaning? From the report, it also sounds like the images were being obtains in a plainly deceptive manner.
Whether or not there is "harm" is beside the point. The point is whether or not people are being deceived, and whether or not we as a society value meaningful autonomy.
