Public transit is dramatically better for disabled and elderly people (and anyone else who can’t easily drive, such as children, tourists, the poor, sick/injured people, ..) than cars.

High-density neighborhoods make grocery shopping much easier for everyone. Here in San Francisco, I have one grocery store 1 block away, another grocery store 2 blocks away, and 3 more grocery stores within 5 blocks. I can do all of my grocery shopping on foot, and I can pick up what I need in a small batch on my way home on any arbitrary trip. If I were disabled or elderly I would probably additionally need a cart of some sort, instead of carrying groceries myself.