A badge is not a monitoring device and a watch is not forced one you. You wear it voluntarily. Its not that monitoring employees is wrong, but there's a way to go about it. You can't force spy devices on a person's body or close to them constantly and win the approval/loyalty of your workers.

Why not install CCTV in the loo while you're at it? Staying inordinately long in there is also a form of slacking. How about microphone to monitor the conversation between workers?

Just wrong. Badges are not voluntary at any corporate office I've ever seen or worked at.

Do the employers of these millions of people have access to the fitbit data? And use it to decide on keeping them employed?

For athletes, I think that's likely. There all kinds of quantitative optimization of training regimes going on, and if someone can't adapt as desired it's likely that their career will be cut short.

Yes, but the incentives are different. I would be more willing to wear one if:

  1. The organization really has my best interests in mind.
  2. The organization paid me millions of dollars to work for them.

With Amazon, I suspect #1 isn't the case and we all know #2 isn't.

Most athletes aren't playing in the big leagues and aren't paid millions of dollars. Frequently they are pushed to perform past their limits or shortly after an injury, so their best interests aren't always considered. Pretty much the most significant difference to Amazon employees would be that they got into the job because they enjoyed it.