[CrimsnBlade]

These engineers seemed to have gained quite a reputation for their work, and were thought to be very valuable to VW. It's possible that the "lots of people" that should have known about the software simply trusted these engineers and their work to the extent that they didn't bother to inspect the software for flaws as closely as they should have.

I can't imagine something this important not having to go through multiple people for inspection. So of those people that are saying they "don't know", though it may be true, for some of them it was their job to know, I think that should (and probably is) being taken into account in the investigations.