Ticketmaster works "well enough" that venues have no compelling reason to switch.

A startup may offer a "10% better" set of features, but that's not enough for the venue to justify the large switching costs and large risk that would be involved in trying out a competing product.

For such a switch to be justified, the alternative product's feature set would have to be 100x better -- a "gamechanger" that fundamentally alters the way the venue does business, not merely offers minor improvements.