Well at least one possible reason is that for live events, the company that has an effective monopoly is Live Nation. And they also own at least one of the platforms where scalpers sell their tickets; Ticketmaster.
I also imagine that as an event promoter, being able to say some variation of "Another sold out show", or "Tickets sold out within seconds" creates pressure for buying early for all future events.
It also takes active planned work to implement these solutions. And if they have a monopoly, they have no incentive to do that work.