This is more so just my personal preference. I listen to them all the time with ear phones.
I'm just an audio addict. Most of my learning comes from listening.
But when you listen to audio, and you have to "reread" or you accidentally missed something, isn't it hasslesome to go back and listen to that part again? I don't have enough faith in my concentration to listen to audiobooks.
I mean, it depends a lot on the reader, but there's something about people reading information that I just "get". That is, I don't ever really zone out when I'm listening, and I can listen for hours, even if I'm not paying attention, what people say just kinds of seeps in to my head. Plus, with tone and the way things are usually written, I can fill in the gaps if I do miss something pretty well.