This is how scarce resources are allocated. There is no fairer way to decide who wants something the most than to ask who is willing to give up the most to acquire it.
> If an event organiser/ticketer wants to use dynamic pricing, that's up to them.
Absolutely. And if a third party wants to buy tickets at the offered price, that's up to them.
Now, this seems unimaginative. Surely, especially given all the feedback and critique on this thread, you can come up with other factors besides price that should influence fairness in this transaction?
We may decide that introducing other factors (like band loyalty or degree of enthusiasm for the show) is difficult, impractical, or threatens entrenched interests, but that's another issue.
We can't let enthusiasm for the allocation properties of markets ("it's Pareto optimal!") bleed over into value judgements about the outcome ("...so we all agree it's most fair!").
What is 'the most' for one may be pocket change for another.
A $200 scalped ticket is a few hour's work for us in the IT bubble. A $100 original ticket is a few day's work for someone on the minimum wage. Who is willing to give up the most in this case?