Unfortunately, evidence [1] suggests that the rate of bug detection by reviewers does not scale linearly with the number of reviewers, adding more than 4 reviewers uncovers bugs at a much lower rate [2].

However I absolutely agree that better / more extensive / diligent code reviews are part of the solution to improve code quality and eliminate these kinds of defects. It's tough to create the right kind of incentive structures for reviewers internally at a company; maybe the future will have specialist firms that provide review-as-a-service for a fee, or perhaps firms could trade review-hours (all under strict NDAs I'd imagine).

[1] Glass: https://books.google.gr/books?id=3Ntz-UJzZN0C&pg=PA174&redir... [2] https://en.wikipedia.org/wiki/Linus%27s_Law