Just recently, Uber (with some partner) started testing delivery robots in my (city) neighborhood. And I love Waymo, as much as I've been able to use them. Maybe automation will change the economics.
Also, IIRC, for many years, Amazon barely squeaked a profit. They wanted to be at the low end of the margins to capture market share. Once they got big enough, they increased their margins a little and started turning a big profit.