These are remarkably close to the raw cost of materials and tooling. The Sagrada Familia model is a 12k piece set for $800, ~$0.07/piece. Phantasy has an unlicensed Opera set (85019) [0] with 3.5k pieces for $190, $0.05/piece. That's straight up cheap. They're not limiting production to control prices. High quality injection molding (in multiple colors no less!) is hard. 2 cents over 12k pieces does add up to a nice bit of change for Lego though.

[0] https://pantasy.com/products/pantasy-the-opera-85019