The Look Inside feature on Amazon is only available if you are distributing your eBook through BookBaby's eBook distribution service. This feature shows 10% of the book's interior content when used by a potential reader. Other retailers with similar Look Inside options also only use the eBook version of your book.
The reason why this feature is only available for eBooks (and not printed books) is because the retailer uses the ePub file that BookBaby sends them to feature the content being displayed. We don't send the retailer print files of the book, as we are the ones handling the printed of the printed books for Print on Demand Distribution, so they have no print file to display.
The Look Inside feature on BookBaby Bookshop is optional, works for both print and eBook, and our authors get to choose which pages display. For more information on setting this feature up on Bookshop, please visit this page.