> don't think 80+ year olds should be driving a car or even operating a McDonalds
Warren Buffett is 96 years old. Knowledge and wisdom tend to increase with age.
Knowledge and wisdom *of recent technology* (or even current events) tends to increase with age?!
Dubitable.
Cherry-picking one unrepresentative billionaire is not a very convincing argument.
Your second sentence is a nonsequitur. At 96, Warren Buffett should be neither driving a car nor operating a McDonalds!
So then surely your grandma will never, ever need help operating a computer or a phone. That knowledge just magically appears with age, right?