Ticketmaster isn't huge in Europe. I think CTS Eventim is the closest equivalent, with a similar share of tickets sold in a few countries, including their home turf, Germany. But I don't think it's comparable, as they're not similarly vertically integrated.
Ticketmaster are enormous in Europe. Pretty much every major artist uses them, and every festival uses them (aside from Glastonbury apparently). If that's not your definition of huge I don't know what is.
I think the lock-in is nowhere near what ticketmaster is doing. Bands don't have to make deals with Eventim, for venues Eventim is typically just an additional way to sell tickets.
https://en.m.wikipedia.org/wiki/CTS_Eventim