Article says this program is opt-in. Does that mean you can decline? If so, I wonder how one does that. I wrote to the CBP years ago when they instituted kiosk

Article says this program is opt-in. Does that mean you can decline? If so, I wonder how one does that. I wrote to the CBP years ago when they instituted kiosks that took your picture to "expedite customs" asking how to opt out. My question was lost 3 times, and finally the response was "there is no way to opt out."