That adds a lot of overhead (who is responsible for marking attendance? How is the refund managed, especially in the case of cash payments?), opens up new forms

That adds a lot of overhead (who is responsible for marking attendance? How is the refund managed, especially in the case of cash payments?), opens up new forms of abuse around how you count attendance, but most importantly doesn't prevent scalping from finding an equilibrium above the ability of a demographic to pay, and I am not even convinced it will stop scalpers from finding price points that have profit for them but lower attendances. I mean, should you need a staff economist to price your concert tickets?