Thats the thing, you're assuming that taking a prep course can help everyone who takes it. The sad truth is, not everyone may benefit from such a course. When I took the MCAT in 2003, I signed up for the TPR class and went to maybe 5 lectures covering topics that I was weak in. The rest of the time was better used on practice problems. I ended up getting a 36. Conversely, I had friends who went to every lecture, and did every practice problem too, but ended up with a 26-28. Wealth does not equate to ones intrinsic capacity to do well on the MCAT.
This concept of rich vs. poor vs. average kid is naive. I have 3 undergrads working for my lab. One is taking loans to pay for her Kaplan course, another is using bookstore resources (Gold, EK, etc) to study at home. All 3 have done well on the MCAT (34 and 35 respectively). Another student took TBR, and was quite conceited about the whole thing. He got a 5 on the VR, and a 21 overall. His parents paid for the program.
Money management skills apply to everyone. There are plenty of undergrads out there who do not have the benefit of parents to pay for everything, or some of it. There are such things as loans and so forth. If they are unable to afford $1800, or even $300, then what makes them think they can afford the fees for primary applications, secondaries, and the flight/hotel stay for interviews? I have seen undergrads who complain about how they can't afford TPR, Kaplan, etc, yet they save up to go on ski trips with their frats, and parties every Thurs/Fri.
I for one took Kaplan the first time I took the MCAT, and then paid for TPR the second time (2003). From 1998-2003, I work to support my family, and myself. I found both prep courses to be useful especially their structured programs. Are you implying that I am not "best at money management"? Am I rich? Nope. However I know what to spend on, and when to save money, hence I have been debt free all my life. I now enjoy life as a PhD student while preparing to apply to med school.
Your assumption that prep courses are a large waste of money is not evidence-based. I'm sure it can be a 50/50 split in these forums on who thinks what. The irony is I attribute my 36 on the MCAT in 2003 to be due to TPR's rigorous practice problems, and adequate teachers. Four years later, with my MCAT now "expired" since doing a PhD program, I took the TPR program AGAIN to access their ONLINE MCAT exams to simulate the real thing. I earn $21,000/year before taxes, pay $805/mo for rent...you think about that one. Personally, if its going to cost me $1800, $3000, $5000 to do well on a test so I can get into a med school where I'll spend $21,000-$40,000/year for 4 years? Yea....trivial.