No one seems to have pointed out that Chris was the main driver of the house for years before, and Barb only started driving again BECAUSE Chris went to jail. She could have had her keys and license taken away in 2016 for all we know. Forgetting that and driving anyway is EXACTLY what you would expect from a non attended Alzheimer's patient.
The stupid "Barb can drive so she's all there!" argument falls apart when you take into account that she GOT IN A CAR CRASH THAT ALMOST KILLED HER! She shouldn't have been driving, she probably did lose her driving capability years ago, case closed.