I think the biggest issue with audiobooks is all the extra people it takes. An author does most of the work on a book, and while advances do exist, they're mostly established authors who already have a known audience. Ultimately, they make money if a book sells. Obviously printing isn't free, but it's not crazy and doesn't scale up costs that much.

An audiobook still pays the author, but it also has a bunch of extra up front costs. You need a sound studio, you need a narrator, and you need audio mastering. All of these cost good money up front, the costs scale up with length. The 45 hour Brandon Sanderson Way of Kings is going to cost a lot more to make than a short 5 hour beach read, and because of the length inherently have lower floors and ceilings on volume than something shorter. You need to charge more to the enthusiasts who want that content to offset the extra costs. I'm honestly not sure if Amazon is using those as a loss leader knowing that those readers usually read a lot of books, or if they're bullying the publishers into giving them a discount, but either way I don't think anyone else can afford it.