It is quite the racket. I'll chime in. I go to a DO school, and I am paying over 55K just in tuition (normal tuition was 45K) for my two months of summer and the entire fourth year. I am not doing any of rotations that are affiliated with my school, although a lot of these rotations are often full with 3rd year students and some of my fourth year classmates have had trouble finding rotations through something similar to a "lottery" process.
I have set up all of my rotations on my own, my school (clinical coordinator) just had to approve them. So, I did all of the leg work through VSAS or through contacting a preceptor/institution. My school basically got 55K to approve the rotation, so yes, it is quite the racket. It is ALLLLLL ABOUT THE $$$$. The school is paying the preceptors that are affiliated with my institution nothing, and obviously not paying any preceptor/institution not affiliated with my school.
And if there was every any doubt that it was about anything besides money and a piece of paper at graduation....why do you think most DO schools (mine at least) get 1 month of "vacation" to study for boards, interview, and take "vacation" (HA). Because they can't charge you for tuition if you are on vacation, which is why they keep you in school for as long as they can. My last day of rotations is 5 days before graduation, whereas every single MD student that I met during my away rotations got 3-4 months off and could enjoy themselves and actually go on a vacation and decompress before residency. Yeah, let that sink in.
If you end up using 2 weeks (ha) to study for boards, which you'll need more time than that if you're preparing to take Step 2, which you should take, that leaves you with 2 weeks of "vacation" time for interviews. For this reason, many students try to schedule rotations with preceptors who are understanding and let you willingly miss clinic/work to go interview since your CAREER depends on it. If you don't have a preceptor like that, too bad, no vacation for you. And, let me point out that this isn't about vacation. It is about having a feasible amount of time to do things that are vital to your success...studying for boards and going on interviews. And, if the school finds out that you did this, actively skipped a rotation to go on rotations just to avoid taking "vacation" time, well then they will grill you on professionalism.
It is quite the ponzi scheme, hence why DO schools are popping up left and right, as mentioned on the DO threads, despite unanimous consensus from the medical community that there needs to be a stop to this due to lack of GME funding and a stagnant number of residency spots.
To the undergraduate students reading this, who are interested in becoming doctors, take a good hard look at MD programs and if you don't get in reapply. The road for DO students is becoming exponentially more difficult, expensive, and painful. I encourage all prospective students to take a good hard look at these threads, talk to people at the schools you are applying to and ask for their honest opinion, you'll know who is being truthful and who is sugar coating it.