[keiferski]

But do you think the "vast majority of kids" take that as their main reason?

No, but many adults take it as their main reason, which leads to more potential "role-models" becoming police officers/fire fighters, which leads to more kids wanting to be like these particular role models. Example: kid grows up admiring his uncle the fireman, who has nice things (always employed) and makes a difference in his community. His uncle might have simply taken the job because of the benefits mentioned in the grandparent post.

Kids don't necessarily need to know the labor benefits of a job, but (I think) they know the types of people that take these jobs, and want to be like them. Of course, it doesn't mean that they'll actually become firemen, but we're talking about the "what do you want to be when you grow up" question, not necessarily what they end up doing.