Mostly because society (at least in the US) does not yet have the protections in place to stop corporations and government agency from abusing automated surveillance. Who has permission to perform mass facial recognition? What are the limits on privacy invasion by third parties or by the government? So far, in the US, the only significant limitations are social pressure against these practices.

That brings me to my second reason for wanting to opt out – even if this facial recognition policy is perfectly implemented, with wonderful privacy guards, it is still normalizing this kind of mass surveillance and data gathering in the mind of the public.

Twenty years ago, I believe most people would have been shocked and uncomfortable with the amount of tracking that occurs today. You also seem quite comfortable with it, and I think you're in the majority. My opting out is a tiny, insignificant vote that I don't think this should be normalized.