I disagree. They used what they had and were certainly researching continual improvement all along. They've had automation wherever they could implement it all over.
The challenge is finding the right human teams to design the automation that will be successful. Engineers with a background in practical robotic automation are not exactly common.
Every major company is in a race to reduce wage cost to 0 and maximize growth and p/e. For amazon their growth and revenue numbers kept growing despite offering above market for unskilled labor, albiet for horrible jobs. They'll continue to try and eliminate as many FTEs as they can until all they employ are people who manage, deploy, maintain, design and implement automatic systems.