I think someone at the EPA should be held liable for their lousy testing practices. They test cars on a dyno, which is far from real-world testing. They would have easily caught this if they tested cars in the way and same environment that they are driven.
I fully expect corporations to try and skirt the law whenever possible, that's why we have institutions like the EPA. Their practices need to be sound and tamper-proof. It's not impossible. It's engineering 101.
The head of the EPA should resign in disgrace for letting this situation get this far.