My company is very particular about the verbiage they use in our contracts. Basically it comes down to:
More likely than not you will not be able to walk in and start taking photos unless you're with an approved vendor or publication, however if it's music you're looking to get photos of I got my own personal start shooting local music gigs happening in my area. Small town bands love photos of themselves, especially if it's cheap/free. Any content to post online is better than nothing, and you can definitely use that to your advantage to practice photography.
Many years ago, I posted a series of concert photos I took of a particularly famous band at the time to my tumblr page and it blew up way more than I've ever seen before. That was at least 10 years ago and I still see them reposted on the various fan pages for that band today.
I suppose it's just part of the deal when putting your work on the internet. 9 times out of 10, people don't give a fuck about copyright when the "Save Image" option is right there for the taking with zero consequences. I'll admit, I've given up trying to fight it years ago and now just see it as part of the process.
This is the ultimate end-all-be-all red flag for any professional photographer. If they don't want anyone else but you there, run in the opposite direction. Even if it's in good faith, you never want to put yourself in a position where you don't have a safety net there with you at all times.
Tell me this isn't real, holy fuck.