People volunteer for all sorts of reasons that fit your description -- b/c they're required by a school/frat, b/c it's a requirement (or even an elective) to ea

People volunteer for all sorts of reasons that fit your description -- b/c they're required by a school/frat, b/c it's a requirement (or even an elective) to earn a badge in boy/girl scouts, b/c they feel pressured by others in their community (e.g. in a church), b/c their parents made them. You may feel that some (maybe even most) people's motivations are less pure than others, but that doesn't make their actions "not volunteer work".