The difference between you reading and the software is one is 'mechanical', whether you want to constrain someone doing that in the rights you grant is debatable.
Copyright enables you (gives the creator the 'freedom' to choose) to make such choices, its what people choose to limit is the problem, as they tend to be very stingy.
The "outcome" (text is read aloud) is the same if you read it aloud to yourself. Really the difference is that when a publisher releases an audiobook they hire someone (sometimes multiple someones) often an actor or the original author to sit in a recording studio and recite. They pay for things like studio time, sound engineering, editing, the narrators time, sometimes music or foley, etc. It's very much a different product.
If you have a book and you recite it, or if you pay someone to come into your home and read it to you, or you get a bunch of software and have your computer read it for you, that's your right and at your own expense in terms of time, money, and effort. Some kind of text to speech software is expected on pretty much every device. Including such features in devices or using those features (especially the accessibility features) of your own devices isn't copyright infringement, shouldn't open you up to demands for payments from publishers, and is in no way comparable to a professionally produced audiobook. Maybe one day the tech will advance to where a program can gather the context needed to speak with and convey the correct emotion for each line and will be capable of delivering a solid performance, but right now we're lucky if more than 2/3 of the words are even pronounced correctly and the inflection isn't bizarre enough to make you question what was being said or distract you from the material.
As a follow up it would be cool, TTS did use different voices for Narrator and characters in a book ... if someone patents that your welcome!
Honestly, if AI ever gets good enough at crafting films from literary source material that the AI movies has any chance of competing with a hollywood production the entertainment industry is screwed. I'm positive that by then whatever crazy stuff that AI is putting out will be everywhere and playing with it would be way more fun than a movie theater ticket.
Different voices would be cool, but who is speaking which line can sometimes be ambiguous even for human readers. I'd be happy with just one voice that didn't sound like a robot or like a human voice spliced together from multiple sources.
Yeah ... so you might be getting into performance rights then ;P
I still expect it'll mean a lot of very amusing outbound voice mail messages.
We recently listened to How To Train Your Dragon instead of reading it to our kids ourselves specifically because it was narrated by David Tennant.