where did you hear that they were? OPPO is adjusting surface flaws in machined components by filling with 3D resin,

Apple themselves, via techcrunch

“During manufacturing, we use AI algorithms to precisely match each individual hinge with its best-fit housing to ensure perfect alignment, and a confocal laser progressively scans the topology of every single unit and 3D prints up to 25 micro layers of a custom photopolymer to eliminate residual waviness,”

Their hinge is using the same tech, in addition to whatever other thngs they’d thrown in.