What part of that is objectionable? I worked logistics at a big box retailer 10-ish years ago, and that kind of thing was completely standard. The feeling was that, yes, the beeps were annoying when you were helping a customer, getting an occasional drink of water, etc., but your (human) supervisors ultimately used their discretion in how they interpreted the efficiency numbers, and could take all that into account. If your supervisor punishes you for taking a bathroom break, that's a separate issue in my book.
What's the alternative? Should companies not measure efficiency, or not care what it is, as some sort of gift to their employees? The time for humanity is in interpreting what the machine tells you and hearing the worker's side of the story.
Likewise, a beep and a statement of fact on a screen ("target has been missed") is a far cry from screaming.
If the work can fundamentally be measured on 15 second intervals, what is the rational basis for not doing so? If your issue is with giving the picker instant feedback on how they are doing with respect to their performance goals, what interval would be more satisfactory, and why?
I understand that, emotionally, it is preferable to receive negative feedback less frequently than more frequently if given the choice, but I can't help but feel that a lot of the unease with the scanners on HN is the result of projecting best practices in one's own field (software development or some other form of creative knowledge work) onto another. We can all agree that beeping at a software developer if they don't type X characters every 15 seconds would be absurd, but we don't scoff at test-driven development, spell-checkers, and other instant performance feedback mechanisms. Most of us don't interpret a red squiggly line in Word as emotional abuse; what makes the scanner beep so much worse?
And if you can find a way to measure joint stress and wear through the day, we can optimize the workers to pick the heaviest parcels each can lift such that it only damages them a bit but not more over the course of a week than nights and weekends of rest can cope for, that would be great too, thanks.
And dim the warehouse lights, they can have individual torches. No sense lighting parts of the room people aren't looking at. Oh hang on, batteries - better make them hand cranked torches, then the power comes from their lunch, ha ha!
The issue isn't with instant-feedback, it's with degradation and treating humans like industrial farm animals. The question isn't "is this effective", but "is this ok?" and "can anyone come up with something less dystopian but still workable? - please?".
What's the alternative? Should companies not measure efficiency, or not care what it is, as some sort of gift to their employees? The time for humanity is in interpreting what the machine tells you and hearing the worker's side of the story.