That assumes the vendor runs a buy-back scheme. That would cost and the cost paid by all ticket buyers, if one isn't in place already.

Openly selling is only part of the problem.

How do you distinguish between someone buying tickets as a gift and someone who sold them on in a manner you did not detect? What about group bookings, do you want the ticket seller to collect full ID of all the intended audience members? After that, what if the group of friends changes - who pays the admin fees?

Your idea isn't terrible, but it is far from perfect.

> If noticing scalpers is easy, the bond doesn't need to be silly high.

That is a huge if. Many scalpers are rather experienced and organised, while some will be very easy to spot I suspect a lot of them won't be, at least not without a bunch of false positives that will inconvenience genuine buyers.