A lot of Wartsila engines claim to meet emission standards without a CAT or scrubbers, a very big selling point, a lot of buyers might claim that rather than have to retrofit CATS and scrubbers they would have bought a different engine in the first place. It would be interesting to know if the particular engines that were incorrectly tested, were "Border Lines" passes on emissions, 1% could make the difference between pass and fail.
Obviously CATS and scrubbers wont remove CO2 emissions!
Same problem as with BP in the Mexican Gulf, the Bankers a few years ago, and VW more recently, if you promise people large bonuses for meeting impossible targets and the sack if they don't, they will find a way to slip out sideways like a bar of wet soap under pressure. No one is going to ask how they met the targets, and the bean counters wouldn't understand.
Management culture is usually "rack up the pressure on people and get results, because the results are all that matter.
The Wartsila L20's on my last ship were supposed to meet emission standards without a CAT or scrubbers, but when the ship was built the owners made a big marketing point about the ship being "Green" and fitted a Cat. However, the ship was a PSV and spent about 1 day a week in Port, 2 days a week in transit and 4 days a week on DP. The exhaust temperatures were only high enough for the CAT to work in transit, so it was only possible to use about 25% of the time. The UREA to inject in it was expensive and difficult to obtain, so in the end the system was flashed up once a month for a couple of hours test and not used the rest of the time.
Wartsila is probably one the biggest engine Builder in the World, over the last few years it has bought up most of the European engine Makers from Sulzer downwards and built huge manufacturing plants in China.
It is always better to ask a stupid question than to do a stupid thing.