My comment was meant more as sarcasm than as a dissertation in economics.
Since scalpers only deal with the price for the excess demand it actually is a good economic model.
Presumably, the promoter sets its price at a figure it determines will generate the most revenue and keep regular customers happy. If the promoter under prices its tickets, there is going to be excess demand. How this excess demand is treated is what scalping is all about. Even if the promoter was able to insure that say, no more than any individual could buy more than 2 tickets, some of those who did not get tickets will pay extra and some with tickets will decide the premium is worth it and will sell and pocket the profit.
Since there is a happy buyer and seller, why should this be illegal.
If some enterprising business person is willing to pay people to stand in line all night to purchase tickets for later resale, hasn't he performed a valuable service to those individuals who want tickets but do not want to stand in line all night?
Shouldn't he be entitled to a premium for his forsight, and risk?