[nextn]

> That assumes the vendor runs a buy-back scheme. That would cost

What would it cost? The vendor runs software that sells tickets. The same software can buy tickets back, invalidate the ticket IDs, and issue new tickets with new IDs. This feature can be part of the software at no additional cost.

Not running a buy-back scheme possible costs more to customers because of today's scalpers.

> How do you distinguish between someone buying tickets as a gift and someone who sold them on in a manner you did not detect?

As the venue/band, you don't need to. Sell to anyone.

As the customer, when you're buying from a scalper you know you're buying at a higher price than the advertised price.

> what if the group of friends changes - who pays the admin fees?

I don't see what admin fees must exist for this. Software manages anything. Printing a new ticket is cheap.

> Many scalpers are rather experienced and organised.

So is law enforcement. Scalpers can't hide the fact that they're selling.