Why are so many people keen on defending VW with the claim "if VW are doing it, everyone else must be"? That dilutes the severity of this problem. I've seen several threads on HN meant to do this.
No, it actually increases the severity of this problem. One car manufacturer cheating emissions vs. most car manufacturers cheating emissions.
Well for one reason, sanctioning one manufacturer for behavior that all manufacturers engage in means that selective enforcement can be used to pick off unwanted competition in the marketplace.