I visited either YYZ4 or YYZ3 a few months ago and I was incredibly disappointed. For a technology company, their warehouses were anything but sophisticated.
Their storage robots were surprisingly lackluster, their outbound/cubiscan conveyor belt was incredibly slow and often stopped.
Of course, I am just an outsider looking in, and I have no visibility into the underlying software that optimizes these process, but when you look at companies with fulfillment tech like JD, you really wonder how Amazon's retail arm is able to survive at all.