Why is Community Service controversial?

I don't understand why student community service is so often challenged or why it is not seen as something positive. Even when renamed "service learning" so as to emphasize the educational benefits, it is still controversial.

I know of a school whose "service" program entails exhorting parents every two weeks or so to send in 3lbs of pasta, two packets of diapers or a 5lb bag of rice. Their rationale is that doing so is not controversial and they can still help their target demographic. My question is how and what do their students learn from this?

I know of another where students play blindfold soccer against a team from a blind school, or go (once) to sing at an assisted living facility. My question is how does this benefit the recipients of this service?

Of course, other justifications may be seen as politically motivated and thus open to debate. Do those with privileges have a duty to those without, a noblesse oblige if you will? As members of a community, do we have an obligation to help those less fortunate in return for the benefits we gain from that community, a social compact perhaps? As human beings, should we not help those in their our of need as changes are one day we will be in need ourselves, a form of social investment?

To me,Community Service has three raisons d'etre: students give of their time; they experience other people who are in need and/or less fortunate than they and they see firsthand particular situations and struggles; and they make a real difference in the lives of others. The educational benefits of each is surely inarguable.