These things should be as reliable as Merlins now.
Merlin’s were developed from before 2006 through 2018 and had multiple failures in their early revisions. Raptor has been under full development since 2012 and has had only three real revisions. It’s not a surprise that a much more powerful and complicated engine is taking a little longer to be production ready.
SpaceX built hundreds of Raptors because Elon’s experience with F9 taught him that optimizing the factory to mass produce something is just as hard as designing it and that he will need that capability for Starship to meet its goals. I’m sure a lot do Raptor V2s were thrown in the trash as the factory processes were developed.