We can't see software.

You can see if a motherboard has twice the necessary components, or if a robot arm just looks wrong, but if your algorithm to process 1000 records takes a thousand times longer than it should (but still finishes in 100 milliseconds) no one notices.

Until it has to process stuff in real-time that is.

A robot arm is exactly the place you see software acting up. If your algorithm is consistently slow it's fine, the moment it's inconsistent things dont line up and problems happen.