So the best workers will be people too. No worries; folks won't be judged or measured as robots. Not an issue.
This is Amazon we're talking about... their warehouse workers are already "judged or measured as robots."
An efficiency metric based on tracking a worker's hand movements within standardized axes of freedom is totally something they would do if they felt there was money to be made.
If this technology was used to find the bottom 10% of workers and correct their behavior or fire them, it would probably be fine.
But there are people who ARE able to maintain almost perfect efficiency for huge lengths of time. Everyone will be measured and everyone will be expected to preform. People in the "normal" range will be made to feel inadequate. Everyone will be getting prescriptions for ADHD meds to compete with the top performers. The top performers will then feel pressured to get the same medications in order to maintain their advantage.
This technology could put a lot of pressure on the system. And it could lead to people eliminating small breaks that might be necessary to maintain their mental health. I guess time will tell. I'm hoping companies use the idea responsibly and think about the long term incentives they create. But that doesn't seem likely.
We are already there and have been for years, for getting into elite universities. Perhaps not yet for warehouse or fast food positions.
Consider if we have three employees. Person X is the fastest, Person Z is the slowest, and Person Y is somewhere in the middle. Consider how management will treat Person Y. For example, both of these sentiments are likely to be used by management to motivate/control Person Y:
"Person X is performing at a quicker rate than you, what can we do to close the gap"
"Don't be like Person Z or you're at risk of losing your job"
If you think that a company like Amazon will do nothing about mediocre performance, you're almost certainly mistaken.
To be honest, if these wristbands are introduced at Amazon, I will attempt to completely boycott Amazon until they're removed. I don't work at Amazon (nor do I ever intend to), but in my opinion the wristbands would be a step too far in reducing working conditions, and set a damaging precedent.