I've thought about one of those.
However, I don't want to lose what muscle tone I have and I will have knee replacements one of these days. Also, that doesn't solve my shopping problem at the grocery story since there's no basket (at least not one big enough) for groceries. I'll probably find a unique solution that fits me one of these days but that doesn't. I could not lift it out of and into the car. Nor would it fit in the car (unless if folds and then where would the groceries go?).