If the promoters want to do this, they could easily enforce it. Sell tickets to specific people, with the name printed and/or bar coded on the ticket. Check IDs at the door and if your ID doesn't match your ticket, you don't get in.
Alternatively, you could associate the ticket with the credit card used to buy it. The card has to be swiped at the door when the ticket is scanned to make sure the card holder is present. That might be easier for kids' shows like this one where the children wouldn't have ID but the parent would have bought the tickets for the whole group.
If the promoters want to dictate the price, they need to find a free-market solution to ensure their product is used by the people to whom they sell. Airlines have done it for decades. But if they choose to permit their product to be used by anyone (and another poster indicated that some promoters prefer it that way, for less than above-board reasons), then the free market should determine the price. The people for whom the tickets are worth the most will get them, because they'll be willing to pay the most for them. This is how efficient free markets work. If you forbid it, you have some people who would rather have the true cash value of the tickets but have to use the tickets, and you have others who would rather see the show than hang onto their money, but they are also prevented from getting what they want.
This is what is going to happen. It is already happening. During the last World Cup in 2006 tickets were sold to specific people with the name of the purchaser on the ticket. ID's were checked against the name on the ticket before entrance to a stadium was granted. It's unfortunate because this sort of thing costs money to enforce and raises ticket costs, but at least it doesn't raise the price to anywhere near the extent that these scalpers do. I for one wouldn't mind seeing arenas and event promoters institute widespread implementation of this.