Amazon is surveying Dash Button users about a Preferred Day shipping discount of 5-10%.
According to the survey the discount would allow users to specify a preferred day for the delivery of Dash Button orders and offer a discount when multiple items are set to be delivered on the same day.
Example:
Have you ever used an Amazon Dash Button? Would a discount encourage you to use Dash more or do you need your stuff faster?
Screenshot from the Amazon survey:
