There is no reason that event tickets couldn't be sold similarly to airline seats.
Charge extra for each armrest. Charge extra for priority entry to the venue. Charge to bring in a purse. Charge to sit next to your family. Charge for adequate leg room. Earn points that become worth less and less as they accumulate.
Charge extra for each armrest. Charge extra for priority entry to the venue. Charge to bring in a purse. Charge to sit next to your family. Charge for adequate leg room. Earn points that become worth less and less as they accumulate.