First off, some people love weird things. They're in the minority, but there is that guy who's running a paperclip factory that's deeply in love with the paperclip...just as in love as the one composing symphonies or helping children. If we're going to evaluate the altruism of an act based purely on internal emotional feeling, they would come out tied.
Second, just because a job serves people, or is counter culture, doesn't make it inherently beneficial. It took me a second to realize and accept this, but there's a lot of selfishness in my martial art. I see no difference in working 50 hours a week to build a bank account and make CEO than I do working 50 hours a week to improve a skill and win a competition. In both cases, you work to serve yourself. Those goals are not wrong, but the path you walk to get there is what makes the difference.
Third, a job being inherently subservient does not then make the people performing said work universal martyrs. I've met some twisted human service people. It's not frequently admitted, but while human service jobs seldom offer much pay, the do offer a LOT of power. A VP can fire, cut pay, and cause some serious emotional damage...but still...a teacher can derail a child's progress in life permanently, a counselor can sexually manipulate, a social worker can ruin lives with one decision, a missionary can abuse the very people they were sent to help. The difference? Vulnerability. People do not open up their souls and emotions in the world of the corporate. Of course those things are affected by sheer exposure, but there is little expectation that a supervisor is trying to improve someone's overall life. That's one very honest things about the coldness of business. It's a contract...work in exchange for money. That contract limits damages to a degree...but in the human services, people are openly and rawly exposed to those around them.That why a person being apathetic about their job in business doesn't bother me too much, but in human services, I find it offensive and irresponsible...possibly even malicious.