That used to be true a long time ago but the game is changed. $25/hour will buy you a junior dev at best who barely speaks English and is 12 hours away. And this developer needs constant communication to be productive. More often than not, you can't get cheap rates like that unless you offshore 20 developers and get a group discount. Usually then there still is a point person you have to communicate with daily, and still you wind up getting a rectangle when you asked for an oval. This is from first hand experience.

For skeptical managers, start with 2 days a week. Standardize on a communication platform like Skype + Google Hangouts. Require the person to be constantly available via IM.

Bottom line, it may be more expensive up front but key advantage to a US remote worker is they are generally always available, highly independent, and it's easier for them to come onsite as needed.