I spent years thinking about how to keep order in crowded streets, and this looks like the digital version of the same problem. If we already have laws against misrepresentation, against bots, against failure to disclose who is selling the ticket, then the first duty is to enforce them properly. A resale cap can help by reducing the incentive for large scale industrial touting, but it will only work if fans have simple, trusted ways to resell at or near face value. Otherwise you will be asking an overworked constable to police a marketplace scattered across apps, aliases and overseas servers.