Whilst not suitable for reference material, audiobooks seems much more suitable for portable usage. No big screen device to carry arround, and you get to keep your eyes for other purposes - driving, cycling, looking where you are walking etc.
At least in Sweden, the audiobook scene have exploded the last couple of years, many books are released as audios at the same time as the first print hardcovers hit the bookstores.
We even have a few online streaming services for listening to audiobooks directly from the phone/computer without the hazzle of first downloading or copying CD discs to the desired listening device.
Not everybody likes to listen to books, and more odd titles propably wont be recorded, but for the titles available it's quite convenient.