Do Volunteers Steal Jobs?

"Low wage workers steal jobs." This argument is one we have all heard. It gets applied to issues such as immigrant labor, off-shoring, even unionization. The prima facie argument is compelling. Someone willing to work for a lower wage replaces the individual working at a higher wage. It isn't fair, etc., etc.  That's what made this post on Econlog so very interesting. The author of the article referred to in the post, indicates that there was suspicion about the motives and effect of volunteers in the aftermath of the Haiti earthquake. Locals thought the workers were "stealing their jobs" by agreeing to work for less than the local wage. When informed that they were doing it for free, a common response was that the workers must be getting paid elsewhere.

The type of thinking exhibited by the villagers may be questionable, but is it a logical extension of the arguments we hear related to immigrants, off-shoring, etc.? If it is true, shouldn’t anyone from the outside who is involved in the cleanup after a catastrophe be looked upon with suspicion? The motives of numerous charities should be questioned because the workers are doing things that locals could be doing themselves and possibly getting paid for.

Would it also apply to help extended during catastrophes? If "outsiders" come to help fight forest fires or build levies against flood waters, aren't they taking work from those in the community whose job it is (or could be) to perform those services?

I'd be interested in reading your reactions. If you've read your Adam Smith (both The Wealth of Nations and The Theory of Moral Sentiments), how do you think he would respond?