Events and industry norms will vary.

Some musical theatres might say on their website: “All shows are protected by stringent copyright laws and taking still photos, video and audio recordings is a direct violation of these laws.”

Big bands performing concerts will probably be stringent re: DSLR photography, and only allow media accredited professional photographers. Smaller gigs I’ve simply asked at the door whether I can take photos for personal use, and have been let in without issue.

I’d do a combination of research beforehand, and contacting those responsible for the event if necessary.

For those visiting in the future, here’s what Mike Brown had to say about it: https://www.reddit.com/r/nba/comments/17jljr9/mike_brown_on_the_keegan_murray/