<p>Higher degrees commonly demand higher salaries, with obvious exceptions. That in mind, a savvy HR department would be wary of picking up too many applications from PhDs; as such, those applicants would definitely have to justify their increased salary more than any applicant in their "normal" pool would, something that someone with nothing but school experience past the BA would have hard time showing.</p>
<p>Of course, having a PhD doesn't ALWAYS mean more money. Sometimes there are more soft causes for rejection: employer feels intimidated, doesn't feel your PhD and the experience you had getting it is relevant enough to override the work experience required for the job, you might be older than others applying for the same job and it'd be more difficult for you to find your place in a peer group (so they think), etc. Of course, several of those are illegal in isolation, but who's to say they don't have some intangible effect?</p>
<p>This is, of course, all from hearsay and interpretation, not actual experience.</p>