Correct. Although it is legal to unlock your phone in the US (it is currently exempt from DMCA), carriers are not obligated to make it easy. And they usually don't.
However, I've heard that this is one of the things that Obama's new FCC is going to look into.
Are you sure about the DMCA exemption part? I know EFF was petitioning to make carrier unlocking exempt from DMCA. Why would they need to file for this if it was already exempt?
However, I've heard that this is one of the things that Obama's new FCC is going to look into.
Edit: In fact there's an article in today's WSJ: http://online.wsj.com/public/b/article/SB125080439024647621....