You’re talking about Anne Sacoolas. There’s more to it: she’s a spook, and she fled on board of US military plane, lying about having diplomatic immunity.
The US always puts it diplomats back on a plane ASAP after that sort of incident. My buddy in the foreign service ran someone over while on a tour and they did exactly the same thing. Back on the next flight out.
It sounds callous, but the person would otherwise become a scapegoat for the US.
People don't normally get incensed over non-DUI car accidents.
People were out for blood because her husband and allegedly she worked for US intelligence agencies. If she was just a tourist who forgot which side of the road she was supposed to drive on the case would just be in the local papers.
You can see it in this thread on hacker news. THEY WERE SPOOKS! STRING EM UP. Uh, no, they were working on a joint intelligence mission with the UK. The vast majority of intelligence workers are analysts and support staff not little green men.
The only reason for mentioning her being a spook is how she used that fact to escape.
https://www.craigmurray.org.uk/archives/2019/10/the-foreign-...
(And say what you like about Craig Murray, he was an ex-diplomat so should understand the rules around immunity).
The US and UK even changed the rule to remove diplomatic immunity from spouses of people at that base after the incident (but not retroactively), which proves she did have it at the time.
Clearly, the parent comment's interpretation is correct in this context. The only other use I've encountered was #3, I believe in James Ellroy novels.
At least the US State Dept position is that she did have diplomatic immunity.
With more civilized countries, the idea is that the person accused is still being tried, but in its country court, with the assumption that if they are guilty, they will get sentenced anyways.