I hate it when companies use this kind of trick to get around legislation or privacy concerns.
"Employees are able to turn off tracking".
Sure, but there is a power imbalance, and employees will come to understand ( although never stated in any handbook ) that the rate at which they disable it will be taken into account in performance reviews.
Just like "unlimited PTO" is not a benefit, because employees self-regulate their use down to less than they'd get if they negotiated a fixed amount.
It's a twisted legal trick to get out of an obligation.
I don't think there are legal concerns with employee tracking. I suspect it would still be legal if they didn't provide an opt-out.
This is the United States, land of the free and home of the slaves. Workers are subhuman here.