Yes. There are a lot of people from associations, organizations and groups who say they aren't paid at all. According to them, they don't need to register. This happens on a regular basis.
Sometimes I tell them to be careful. These people belong to associations and all claim to be volunteers, but they wouldn't be in that association if it weren't for their employer. So I tell them that, if the communications benefit their employer, and not just the association, they must register.
My goal is not to prevent volunteer groups from contacting you or to impose an obligation. We have to find a happy medium. Some organizations are truly made up of volunteers, while others are associations whose members claim to be volunteers.