Is it normal for a PhD advisor not to read a student's thesis?
"All of the papers in the thesis have already been written, so he knows what's in the main body, and I've just been sending him parts of the introduction/literature review."

If this is the case, then indeed it is reasonable (and possibly normal) not to read evolving drafts of the "thesis". Since the thesis is basically done, and now you simply wrap the papers up to have a "thesis". 

I don't think it is essential for scholars to read carefully introductory parts of their students' dissertations, assuming they already read the papers on which the thesis is based. The papers are much more important than a "thesis", which is mostly an internal document nowadays (this is subject specific though, and I'm sure some commenters here would find my answer blasphemous. But I stand behind my position: a thesis is not something important once the papers were written and published or checked).