Do people not Google for alternatives? I can think of at least 5 competitors to Ticket Master. There's even one that only charges 5% seller fee and no buyer fee.
Going with another vendor is a gigantic undertaking, you would need to overhaul most of your processes. Most venues don't have the resources/bandwidth to pull that off.
And that's how TM stays a monopoly.
Source: used to work for a large venue.
Not in the US you can't. And certainly not for venues large than a club.