Get the impression that, like most other things in the legal spectrum, there are more exceptions than there are rules. I would not like to be in the shoes of a reviewer, who can put my employer at risk by accepting an image which can put them on the wrong side of a compensation claim (and damage their reputation). So I guess they follow the golden rule, when in doubt, reject (and some site's reviewers are probably, correctly or incorrectly, more cautious than others).