It seems you don't understand the difference between a conviction and serving a sentence. She was convicted, but has not served any time. Your own link confirms

It seems you don't understand the difference between a conviction and serving a sentence. She was convicted, but has not served any time. Your own link confirms that she was convicted. The equivalent crime in the U.S. is "vehicular homicide" which is a state-level crime. The general sentence for that in the U.S. is usually a suspended sentence of 1 year or less, unless substance abuse or extreme negligence was involved, so she's effectively serving the same sentence here as she would in the U.S., i.e., none. (Yes, the U.S. is very lenient about this.) That's why the U.S. won't extradite her. Over here, she wouldn't have served any time for what she did, and the U.S. generally won't extradite citizens to countries where the punishment for the crime is significantly in excess of what it would be in the U.S. This usually works against the U.S., as many countries (including the U.K.) frequently won't extradite to the U.S. because our punishments are harsher. If she ever travels to a state with an extradition treaty with the U.K. that also has a vehicular homicide equivalent, she can be extradited to the U.K. to serve actual time. The U.K. has one of the largest extradition treaty networks, so basically she's prohibited from traveling outside the U.S. But you know, keep ranting about the laws without understanding how they work. It will serve you well in life.