https://techcrunch.com/2019/03/01/amazon-stops-selling-stick-on-dash-buttons/

Amazon has confirmed it’s retired physical stick-on Dash buttons from sale — in favor of virtual alternatives that let Prime Members tap a digital button to reorder a staple product.

It also points to its Dash Replenishment service — which offers an API for device makers wanting to build Internet connected appliances that can automatically reorder the products they need to function — be it cat food, batteries or washing power — as another reason why physical Dash buttons, which launched back in 2015 (costing $5 a pop), are past their sell by date.