Not really sure how they could do better explaining its purpose. This clearly isn’t meant for the average consumer. Just as a raspberry pi isn’t either, but thats available for purchase on amazon as well. From the detail page:

What the hell does that mean (‘fees beyond hardware purchases’). It allows you to connect the button to an AWS lambda function which is extremely versatile and your cost is only based on how much the function is run - likely to amount to pennies. You shouldn’t scare people away from trying to use this.

Please do your research before completely giving up on active listening devices. The echo does not transmit any audio to the cloud until the wake word is heard. This can easily be verified by checking network requests made to your router.