@opus - one comment:
Whether or not the student has earned income, the rules are quite restrictive and most students are not going to qualify for the refundable AOTC credit. What the IRS did in effect was eliminate the typical college student - under 24, not married, at least one parent living,etc. - from refundable credit eligibility.
This is the unique case where a someone can state they CAN BE claimed by someone else (even though no one actually claimed them) and still be eligible for AOTC.
Parents who have income exceeding $180,000 are not eligible for AOTC. I've always believed the restrictive rules for students is so that a parent who earns more than $180,000 doesn't decide to forego claiming their child (and forego the $500 dependent credit) so that their child/ student can pick up the $1,000 refundable AOTC credit. The student could still pick up the non-refundable credit (max $1500), depending on their tax liability.
