Amazon Tablets are not a failure. They’ve sold tens of millions of these and generated hundreds of millions in consumption / purchases through them. They were the company that first brought tablets under the $200 price point, back when everybody else was charging $350 - $500 (forcing everybody else to follow) and had sold over a million by February of 2012, while still in the infancy of product development.
By April of 2013 they eclipsed Samsung’s market share and sales have grown exponentially every year since. They finished out 2017 as the world’s 2nd largest tablet maker / brand and grew over 50% in that holiday period alone.
They are solid, durable and inexpensive. They make a 7" cheapie you can throw in your glove box for stops at the coffee shop & a quick check of email, Instagram, etc., an 8" cheapie to throw in your carry-on for Airports & on the Plane, 10" with “show” and several kids versions (of which they sell millions).
Amazon did exactly what they wanted to do with this product, it has been a huge success for them, they have an army of millions who love them and have generated billions in consumption.