This is, imo, the most important part of the article. If we want more payments were made without using cash, we have to realize that some people, elderly in particular, probably will never adjust to that. The security guard in question is a hero imo, and we need people like him in every store if we want the transition to be as painless as possible. Also, every place with a sign "We accept Bitcoin" have to be always happy to accept cash as well. Only this way we can avoid unnecessary hostility towards its usage.