Because I hate housework.
I started listening to audiobooks because I had a data entry job right after college where I could listen to a walkman (personal cassette player, for you young-uns) while working. Then I continued because I had a forty-five minute commute to my first professional job.
Now I do it because being a wife and mother, working outside the home or not (I've done both), requires that I do a lot of things I'd rather not do (dishes and laundry), and I do them endlessly (dishes and laundry, dishes and laundry, dishes and laundry...). Audiobooks keep me from going insane when every time I turn around the sink is full of dishes again.
I do get that sitting and reading a book is relaxing, but for those of us with no time to relax, audio can be a lifesaver.
Current thing saving my sanity:
This one might turn out as good as Whale Talk, also by Chris Crutcher.
What about you? How do you find time to read? Have you tried audio and it did/didn't work for you?