The most expensive problems are those that customers or interested third parties discover. If companies try to sweep them "under the rug," or invest resources to deliberately deceive the public, there is likely to be a big explosion as the pressure builds under that rug. This is what has happened to VW.
Time discovers truth, though sometimes it can take years to be discovered. In the case of Volkswagen, who started selling their first emission-test-cheating diesels in 2009, it took six years for the truth to be revealed, and now we all watch in disbelief as a giant in the auto industry comes tumbling down.