VW's code looked for things like (lack of) steering input, the fact that the car is stationary during the tests, etc.
What did Cummins' device do? If their statement is that they saw "no evidence that anyone acted in bad faith", is there any reasonable way that could possibly be true? We didn't let VW get away with any statements like that.
No. Automotive development is cost and time sensitive while also having a large regulatory compliance overhead. Every fraction of a cent matters. Every man hour spent on development and testing matters. Designs are peer reviewed. Processes are tracked and logged. A "feature" that significantly alters the performance of a component under certain conditions does not secretly or accidentally get designed, tested and deployed. Every modern component and system is modeled, characterized and tested thoroughly.
> Today, the Justice Department reached an initial agreement with Cummins Inc. to settle claims that, over the past decade, the company unlawfully altered hundreds of thousands of engines to bypass emissions tests in violation of the Clean Air Act.
https://www.justice.gov/opa/pr/statement-attorney-general-me...
To your parent point, that would be an absence of a feature or a feature that takes less development.