So it appears I misunderstood above: the non-QEE scholarship is unearned income for the purposes of calculating kiddie tax, but is earned income for the purposes of calculating the standard deduction. Wow this is complicated!
So the student’s standard deduction if a dependent will be earned income (from a job) plus their non-QEE scholarship plus $350, the total not to exceed $12000.
In most cases (without a huge scholarship or significant additional earnings) it therefore seems no tax will be due. Then the benefit from being a non-dependent will be minimal unless the student wants to claim the refundable part of the AOTC because the parent can’t.
And it appears the increased standard deduction in the new tax law is a big benefit in reducing kiddie tax on non-QEE scholarships (especially as the room and board component of a full ride will usually be more than the old $6350 deduction). It actually means there are fewer situations in which ensuring the student is non-dependent is worthwhile.