Enabling this like Ticketmaster enables selling tickets.
In ticketmaster's case I believe they give kickbacks and lucrative exclusive contracts with large venues, to squeeze smaller ones, maybe making whole tours use it but only kicking back to the biggest or select venues on the tour I think.
Apple sometimes does special deals and special rules with important providers, among many other tactics behind their moat. All single signons must also offer apple single sign-on, for instance, and they have even disabled access to customer accounts using their single sign-on for unrelated business disputes, though they walked it back in the big public example I'm aware of, the threat is there if you go against them in any way.
