We don't know that she wasn't.
There seems to be something going on with modern diabetes mangement.
There are several isulin using diabetics in my family and I don't remember this frequency of low blood sugar episodes in the past.
The currenrule is to test before getting into the car, get some carbs is the sugar is as low s normal...IOW drive on a slightly high sugar level.
I believe they have improved insulin over the years. I've had diabetes for 30 years and have had my share of insulin reactions. Never while driving, thank God. I always carry in my car a very sweet drink with the cover very loose. I currently take a Humalog Mix 75/25 and sometimes my sugar will go as low as 38 and all I feel is a slight shakiness. My doctor once told me it's an incrediably hard balance to achieve as we must take into consideration food, exercise and insulin. And if all that isn't enough, we had a cat who developed diabetes, and I had to give him one unit of insulin per day. The cat was 18 and I do think it was "old age diabetes". I never minded testing and taking insulin - it's the insulin reactions that I hate.