When I write about monopoly power, one popular complaint is that the issue feels too remote and abstract. Antitrust law is bound up in confusing terminology and complex measurements like the Herfindahl-Hirschman Index. But I reject the notion that people have no personal experience of how monopolies affect their daily lives. Have you ever bought a concert ticket?

If so, then you know the feeling. You waited weeks for tickets to become available, only for them to sell out in minutes—and then appear shortly thereafter on reseller websites, at a huge markup. Or you managed to get the tickets into your shopping cart, only to discover while checking out that there’s a hefty “processing fee.”

These are functions of monopoly. As a Government Accountability Office (GAO) report released on Monday shows, one company dominates the primary market for ticket sales and another dominates the secondary market. The failure to stop them from getting bigger and more dominant will only compound the problem.

Live Nation is by far the largest ticket provider in America, thanks in part to President Barack Obama’s Justice Department, which approved the company’s merger with Ticketmaster in 2010. Ticketmaster controlled over 80 percent of the market before the merger, and that holds true of Live Nation today, buttressed by its role as the nation’s largest concert promoter and owner of over 200 venues. Because Live Nation manages over 500 major music artists, they can demand that venues wanting to host concerts exclusively use Ticketmaster instead of a competitor.

The Obama administration’s settlement with Live Nation was supposed to prevent this. “There will be enough air and sunlight in this space for strong competitors to take root, grow and thrive,” said Christine Varney, then head of the Justice Department’s antitrust division. Remedies included Ticketmaster licensing its ticketing software to competitors, and selling off a subsidiary called Paciola. But the software quickly became obsolete, and Paciola remained a minor niche rival. Meanwhile, the combination of ticketing, artist management, venues, and promotion proved too much for anyone to compete. And that enables the ticket racket.