I volunteer at an ER, and I'm not a kid. I think I could easily get hired as a paid employee, but I then would have all the stress of being supervised and being 100% productive. While I do work hard, and for free, I can take 15 minutes to talk to patients about their treatment, or various staff from the administration to doctors and nurses about their roles, and accomplishments, and how they view medicine.
To say that volunteering is a waste of time is pretty short sighted, in my opinion. Here's a quote which brings this whole humanity perspective home. From an article by Fitzhugh Mullen, author of White Coat, Clenched Fist:
It is not easy to be a good doctor today. It is not easy to work within the profession and maintain one's sense of humanity, one's humility, and one's commitment to service....
The first battle will be against the forces of complacency, laziness, and fatigue and will have to be fought almost daily during one's career. The enemy will make it too easy for you to become insensitive, curt, greedy, prejudgmental, racist, rich, brusque, and thoughtless.... Imperceptibly, one will cease to be a doctor and become a 'doctoroid.'
A 'doctoroid' is a bright, young physician with good MCAT scores, good grades, excellent subspecialty electives, commendable National Board scores, Board certification in one of a number of specialties, and an essential inability to deal with people or communities. A 'doctoroid' sees its medical degree as a game of tennis - a hard won personal skill to be used primarily for self-gratification. A 'doctoroid' is well-to-do, dresses like a doctor, sounds like a doctor, and behaves like a doctor but it has no heart. Inside it is all bank accounts....