It's an interesting thing about money. It's important and everyone needs it, but it can also be a hindrance. For organizations and even individuals, money brings obligations such as the need for stewardship and fiscal responsibility, or accountability to the source of the funds.
Money can also set limits.
Once you've promised how you are going to use the money, you may have little flexibility in changing your course or methods. We all know the problems that arise when, in trying to get money, an organization develops a project simply to attract a funder rather than doing what is most necessary and finding a funder to support that. Perhaps the most unique thing about working with volunteers is our perspective on cash. We don't need it, or at least we don't need as much of it as other departments do. Of course we know that there are costs for and to volunteers but there isn't the same level of spending that is seen in other parts of an organization.