WATCH: Senate questions Ticketmaster business practices following Taylor Swift ticket issues

Senators grilled Ticketmaster Tuesday, questioning whether the company's dominance in the ticketing industry led to its spectacular breakdown last year during a sale of Taylor Swift concert tickets.

Watch the hearing in the player above.

U.S. Sen. Amy Klobuchar, a Minnesota Democrat, recalled piling into a friend's car in high school to go to concerts by Led Zeppelin, The Cars and Aerosmith. These days, she said, ticket prices and fees have gotten so high that shows are too expensive for many fans. Klobuchar said ticket fees now average 27 percent of the ticket cost, and can climb as high as 75 percent.

Klobuchar said Ticketmaster's market dominance means it faces little pressure to innovate and improve.

"To have a strong capitalist system, you have to have competition," Klobuchar said in a hearing of the Senate Judiciary Committe.

Ticketmaster is the world's largest ticket seller, processing 500 million tickets each year in more than 30 countries. Around 70 percent of tickets for major concert venues in the U.S. are sold through Ticketmaster, according to data in a federal lawsuit filed by consumers last year.

In mid-November, Ticketmaster's site crashed during a presale event for Swift's upcoming stadium tour. The company said its site was overwhelmed by both fans and bot attacks. Many people lost tickets after waiting for hours in an online queue.

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Ticketmaster required fans to register for the presale, and more than 3.5 million people did, a record for the company. Ticketmaster eventually canceled a planned ticket sale to the general public because it didn't have enough inventory.

In 2010, Ticketmaster merged with Live Nation, a Beverly Hills, California-based entertainment company that produces live shows, festivals and concert tours.

Live Nation's President and Chief Financial Officer Joe Berchtold apologized to fans and to Swift on Tuesday, and said the company knows it must do better.

But Berchtold insisted that Ticketmaster doesn't set prices or service fees for tickets or decide how many tickets will go on sale. Service fees are set by venues, he said; Live Nation only owns around 5 percent of U.S. venues, he said. He also said Ticketmaster has lost — not gained — market share since its merger with Live Nation.

Berchtold said the ticketing industry would like lawmakers to focus on the growing problem of ticket scalping and prohibit fraudulent practices, such as resellers offering tickets that haven't officially gone on sale yet. He also said the industry should be more transparent about pricing and fees.

Diana Moss, President of the American Antitrust Institute previously told PBS Newshour how the Live Nation-Ticketmaster merger from 2010 creates a major monopoly.

"That merger [has] a wingspan that covers everything from artist management, to concert promotion, to venue management, to ticketing. And when you put a firm together that has that kind of market power, the exercise of that market power, whether it be through threats to concert venues if they don't take Ticketmaster as their platform, or whether it is high ticket fees to consumers, we are seeing all of that market power."

— Dee-Ann Durbin, Associated Press