Using computers is now a basic necessity for life in modern societies, on par with reading and writing.

I think the answer for people who do not have or for some reason cannot use computing devices is to provide places they can go and be assisted (we have those in France called "maisons de service").

I don't think you can design everything around the lowest common denominator (in terms of language or computer literacy) but you can provide ways of obtaining assistance for those that can't manage by themselves.