I would think they have elite testing and QA team to make that happen

Maybe counterintuitively, most big tech companies have no dedicated QA & tester roles, rather, they encourage engineers to think about software quality while developing product.

See the book "How Google tests software" (by James A. Whittaker, 2012) and the Pragmatic Engineer blog has a good post on how big tech does QA: https://newsletter.pragmaticengineer.com/p/qa-across-tech