I know authors are clamoring for preorders for Indie titles, but they know that Amazon might be reluctant to do that for fear of fraud. I had an idea though.
Why doesn't Amazon do a thing called "Pre notifications". When you create a draft book, you can opt to "Publish Pre Notifications Page". This creates the page as-per normal, but the "Buy it now" button is replaced with "Receive notification". This costs nothing.
Then, when the book comes out (is first published), anyone who's hit that button gets the automatically generated Kindle sample pushed to your Kindle along with an email notification ("Wool 5: This Time It's Personal" is now out! Check your Kindle for the preview!")...?
There's a buy link inside the sample, so it's simple and easy for people to buy books they're waiting for, and it gives people a chance to change their mind (or to not buy if their financial situation changes, like they lose their job). It protects buyers from fraud (paying money for a book that never appears).
On Amazon's side, they could make it so that if you enable prenotes, you are automatically enrolled in KDP Select for that work.
It'd be nice if there was some way to check how many prenotes you had, though.