Cameras at events, and who actually agreed to be in the shot

Something that has been putting me off going to anything. I do not want photographs of me in latex existing anywhere, at all, for reasons that are entirely to do with my job and nothing to do with shame.

Every event listing I look at has a gallery of photographs from previous nights, which suggests cameras are normal at these. What I cannot tell is how it works in practice. Is everyone in those pictures asked? Do people get to say no? Can you go to an event and reliably not end up in the background of something?

If anyone runs these or goes regularly, I would really like to understand how consent is actually handled before I commit to a ticket.