Ticketmaster works for the venue, not the event. If a band wants to play in Boston's TD Garden, they must sell their tickets through TicketMaster. For the most part, ticket revenue goes to the event. Fees go to the venue. It's in the best interest of TM and the venue to charge more.

StubHub rakes from both sides of the secondary ticket market just because they can.

(plug: I'm trying to change this, slowly but surely, with my own project: http://www.boxrowseat.com)