Why Aren't Correction Articles Free?

Update (1/31/14) - Tweet from ACS Publications:

@SeeArrOh Corrections are considered additional materials, but we appreciate your feedback and will take it on board.
— ACS Publications (@ACSPublications) January 31, 2014

This morning, a friend pointed out an interesting bit of data in a recent Organometallics Correction article. I clicked on over, only to find myself stuck behind the ACS Pubs paywall:

$35.00! This left me with a bad taste in my mouth, and an obvious follow-on question: Why aren't Correction articles free? Are they peer-reviewed? (Don't think so). Do they contain amazing scientific advances? (Not usually).

Here's the correction process at a few other publishers, for comparison:

Angewandte Chemie Int'l Edition

Tetrahedron

Nature Publishing

What's the deal, ACS?