I certainly do not approve of the scam and deception VW did (and possibly other automobile manufacturers?), but I think I do not approve extraditing citizens of your own country for some non-capital crime. Or even some capital crimes for that matter. I (and most of the other Germans and EU citizens [1]) oppose death penalties. So extraditing someone to the US, which could result in death penalty if someone committed a murder, would be a really big ethical and/or diplomatic issue.
https://www.theguardian.com/us-news/2016/nov/09/british-trad...
https://en.wikipedia.org/wiki/NatWest_Three
The US doesn't always gets what it wants, for example with Gary McKinnon: http://www.bbc.co.uk/news/uk-19957138
To have to navigate the juridicial system in another country is a huge disadvantage. You will make errors which a native will never make. You will not know about options that are very clear to long term citizens. Etc. Etc.
All in all, whatever the crime, you would like to have everybody the same chance in your juridicial system. Foreigners will have a disadvantage however.
All of that is the lawyers' job, not the defendant's, and these guys will be able to hire very good local lawyers.
No judicial system composed of humans can ever be perfectly fair and free of bias, but that doesn't mean we should let criminals go free.
Article 7
EXTRADITION OF NATIONALS
(1) Neither of the Contracting Parties shall be bound to extradite its own nationals. The competent executive authority of the Requested State, however, shall have the power to grant the extradition of its own nationals if, in its discretion, this is deemed proper to do and provided the law of the Requested State does not so preclude.
In fact, Germany has quite a few outstanding arrest warrants against US citizens, too: https://www.theguardian.com/world/2007/jan/31/usa.germany
(0) https://en.wikipedia.org/wiki/Technischer_Überwachungsverein
(1) https://de.wikipedia.org/wiki/Abgasuntersuchung (non english WP link, basically it means "emission checking")
Edit:
VW sold approximately 475000 affected diesel vehicles in the US (compared to approx. 84.5 million car sales in the same time period).
And while this hasn't been public knowledge, it is not that surprising, because it has been public knowledge how much the mileage tests are gamed, so it's not surprising that all other tests are gamed as well (and, specifically, using defeat devices is also illegal).
https://www.theverge.com/2017/7/24/16021292/german-car-compa...
Now, yes worldwide 100,000's of people die every year from air pollution but simply giving up is a poor solution. Further, you can't make getting caught have similar penalties vs. cheating or you promote cheating as having zero downsides.
>any sudden punishment of violators from outside reeks of market protection.
Perhaps it's because the EU lacks the authority of the member states to regulate & police emission laws. They started legal proceedings against their member states precisely because of their inaction.
"The European Commission on Thursday began the so-called "infringement procedures," calling Germany, Britain, Spain and Luxembourg to account for not imposing the same kind of penalties Volkswagen faced in the United States for using illegal software to mask health-harming emissions."[2]
Isn't that market protection as well?
[0]: https://www.nytimes.com/2015/10/15/business/international/co...
[1]: https://en.wikipedia.org/wiki/Vehicle_inspection_in_the_Unit...
[2]: http://www.dw.com/en/eu-launches-legal-case-against-germany-...
And yes, when emissions testing switched to relying on the OBD codes, all was lost. Even I thought about hacking the ECU to report "all good"
http://www.autonews.com/article/20160307/OEM11/303079956/aft...
There's an exception for other member states of the European Union, but that's it.
So when the problem with the overly large AdBlue tanks came up, the Europeans knew they can cheat that away, because legally they thought they can get away with it. The engine test passed legally, and there was no legal framework to protect actual sold cars from emitting too much NOx. This is of course entirely the fault of the politicians, which were of course lobbied into that, and didn't ask much. That's why VW insisted all the time that they acted legally in Europe. In the US of course not, because in the US the big three always had the advantage of special drivers to pass the emission tests. So they still don't fear any legal woes in Europe.
So the strategy is to keep calm, and protect the rest of the industry, the politicians, the workers, change the ECU's, and either add bigger tanks or change AdBlue more often. It's insane to ask for 2 years AdBlue storage anyway. 6 months if enough. And the good engines can pass the new EURO 6 limits, because their injection system is highly optimized. Those engines are miles better and more effective than a normal otto, which enables them to actually use the crap diesel oil. Problematic are only the overly large engines or the cheap ones.