Why is it so difficult to create an effective online ticketing marketplace?

Using the recent TicketMaster “meltdown” for the upcoming Taylor Swift tour as an example, I’m still stunned that for a company whose actual business is selling tickets they can’t manage to create a scalable platform that is bot-proofed?

This has been happening since the birth of eCommerce. ”Back in the day” when you camped out in line at the local Ticketron point of sales office they’d sell you as many tickets allowed and then on to the next choad waiting behind you. Simple, cheap, efficient. But now? Why???