I actually believe firemen should be paid for what they do. But I also believe people should be paid for their labor regardless of what they do. Some taxes are good.
That said, sometimes people volunteer because they want to. That is totally acceptable as long as it is truly volunteering and not forced volunteering (i.e. some university programs require students to "volunteer"....Require and volunteer cannot be used together).
Twice a week? 14 times a month?
Many of the truths that we cling to depend on our point of view.