It's true, but making sure that the tests perfectly cover the product requirements, and making sure that the specified product requirements actually match the e

It's true, but making sure that the tests perfectly cover the product requirements, and making sure that the specified product requirements actually match the expectations of the product are both barely solvable problems for any sufficiently complex product. Trying to keep pace with most markets, it's hard for software developers to maintain detailed enough requirements to even hope to ever achieve exhaustive automated testing.