Most have poor vision and hearing. I am in my early twenties and am instructed to help them as much as possible. Given an alternative, most seniors with impairments I've encountered prefer not to drive. Unfortunately, public transportation is often poor or non-existent. Additionally, families of these seniors frequently live out of the area, are working or don't care.
Most people like to be independent - regardless of age or physical limitation.
Offering to drive them makes it easier on them than their having to ask or beg. I believe older people don't want to face the fact that they have to be helped so much. To them, it must seem like yesterday that they ran around the yard with their kids and drove them to school and tied their shoes, and I'm sure it must be a little humiliating to have to be driven around and have somebody help you all the time. It's like giving all of your freedom up. Many Mexican males I see over the age of 13 wear mustaches.