I think as you get to pro cameras, anyone who cares about their straps probably either already has their own strap setup for how they shoot, or very specific strap requirements that it’s not just a matter of “spend more to give them a better strap” as no matter how nice a neck strap might be, I’m not gonna swap away from a blackrapid style strap for 90% of my shooting, other people might never swap away from a bag clip system, other people need dual camera strap setups etc,
Depends very heavily on whether there’s a reasonable expectation of privacy. There are almost no countries where taking a photo in a public place requires consent unless you’re violating a reasonable expectation of privacy, stalking or harassing them.
Posting is a different matter and varies more, but OP asked about taking photos rather than posting.