What's changed?

IT's not the concert, it's the arena

I see earplugs are not on the list, a relief!

If I attend an indoor concert, I take my phone and money, and that's it. 

Wow, but most seem understandable. Wonder if they frisk everyone for snackbars in their pocket though.

They certainly do check everyone extremely carefully. Things sometimes  just begin to relax slightly when another atrocity occurs such as the Manchester Arena bombing. 
It's not worth the risk for the venue to allow anything  to be taken in. Much like airlines, it's not just to rip us off by having to buy drinks inside, it's because they can scan track and scan their stock of refreshments before they accept it.