...yet you have a phone (for the moving barcode and whatnot) which is heavier and bulkier than a card?

True. I feel it, it's locked without my face and I can track it.

Have a picture of your ID on your phone, like every other person has. Or bring a photocopy of your ID that you can throw away after entering.

I don't.

That's not valid. And almost no one would except it. The real digital version is still in the making.

I knew this comment would come. But you're wrong. A photo of your ID is accepted almost everywhere, and especially at a ticketed event where the only purpose is to match your face to the name on the ticket. They're not the police, they just want to check that you're the person who should have the ticket.

Well around here if they ask for an ID, passport or driving license they don't accept copies. You are wrong on the "almost everywhere". Might be true for most places around you.