>Imagine someone asks you: see that guy across the street? Do I have your consent to search his pockets? If you say yes, what does it mean? Precisely nothing.

I think if you have some kind of authority over the place where this happens and/or if you facilitate an illegal action then you could be breaking the law.

Well, you are not in an analogous position of authority with regard to some licensed stock images or whatever. You are not the guardian of their copyright, charged with defending them from illegal copying. You were licensed those images knowing that the world-wide public will fetch copies of these images and do whatever they want.

If you signed some agreement whereby you pledge to protect licensed images from AI scraping bots, then signing off on a consent to Meta would breach that agreement.

There is no such agreement. Licensees of images are understood to be broadcasting them to the entire world, including anonymous visitors.