Yeah, that was my assumption as well. But upon reflection, I fear they don't have the expertise to tell the difference between quickly-obsolete texts and those that are more timeless. It can be bewildering even with expertise in the field, so I don't begrudge them the difficulty. But maybe you're correct that they have a better knowledge of what is useful to the local community, and perhaps decided these were too academic and sent them to a university library instead. But personally, I think it's a bummer that a curious kid won't see SICP on the computing shelf, rather than five or six books on ColdFusion and the like.
Alternatively it could have been sent to another library in the county system.