The dumb robots fall into the holes, while the smarter ones survive and breed.
From the YouTube description:
Chinese delivery firm is moving to embrace automation.
Orange robots at the company's sorting stations are able to identify the destination of a package through a code-scan, virtually eliminating sorting mistakes.
Shentong's army of robots can sort up to 200,000 packages a day, and are self-charging, meaning they are operational 24/7.
The company estimates its robotic sorting system is saving around 70-percent of the costs a human-based sorting line would require.