The article indicates that the ambulance driver stated that he slowed/stopped before entering the intersection, checked it was clear, and then proceeded. The ambulance hit the Porsche Cayenne in the driver's door, and hit it hard enough to drive it through the intersection, onto and across the sidewalk, and into a tree. Call me crazy, but I think the ambulance driver made an inaccurate statement to the investigators. A Cayenne is not a small car. To knock it that far means it was a hard impact, which means that the ambulance was moving at pretty good speed as it entered the intersection against the red light. Now, add to this the fact that the city has created a driving instructor for the department, revamped its policy, and taken other corrective measures. That means there was a flaw in what was already there, and a need for a revamped policy/procedure manual and an instructor on that policy/procedure. So, the witness for the city lied to investigators, and there was a flaw in the existing policy/procedure. That's why the city settled. In lawyer talk, it was time for the city to get out the checkbook, which is what they did.
And, if plaintiff had a good lawyer, like MillCreek says, all the more reason to negotiate a settlement.