[maddz]

So the moral of this is to check 'Product details' before buying. If you see an entry for 'Simultaneous device usage: unlimited' between 'File size' and 'Text to speech', you're OK to buy. If not, try purchasing the book elsewhere and hope you can match (or better) the Amazon price.

I checked various books in my Kindle library, and it's hit or miss whether a title has 'Simultaneous device usage: unlimited' enabled or not. I rather suspect it's down to whether the publisher has allowed it or not; even books I purchased in 2013 generally don't have it.

This does have implications for people who need to use something like a Braille reader for their reading. It may actually mean this is contravening accessibility rights legislation.