OT is a great field, and I'm not in it for the money, I really do want to help people and that is why I am working so hard. That said I do find it perplexing that our pay isn't much better than nurses, and we have to have similar GPAs to medical school applicants. OT used to be a BS degree just a few years ago, and now there is talk of it moving in the direction of PT towards a doctoral degree. I find it perplexing that with increasing need of OTs and PTs (with a huge boomer generation needing us) that standards and cut offs are getting higher and higher. There will be a point where the raw cost benefit analysis just won't be worth it to many students. Someone with a 3.9 and perfect community service can go and become a doctor, and make about 3-5 times what an OT makes.
It's oversaturation of higher education. Higher education in the U.S. is a profitable business, not a public service. Universities are privately owned and funded. It's like the manufacturing industry. Produce greater quantities of products at lower manufacturing costs and you can maximize your profit margins.
It's reportedly one of the reasons why tuition has increased so drastically, as this is one of the mechanisms that control supply and demand. The other control on supply/demand is admissions requirements and criteria.
So, the higher admissions requirements/criteria is there, because they can put it there. It doesn't matter if these requirements are similar to medical school requirements, they can demand a GPA of 3.8-4.0 so long as there is a large enough supply of applicants. The two professions in this context are unrelated.
You're presumption about a doctor making 3-5 times what an OT makes is rather inaccurate. They take out 200k-300k loans for medical school, make 40k during residency, and start out at around 90k per year at entry level. Then add overhead costs and other fees. Yes, you could make 400k per year as a neurosurgeon. But that is median level salary, not entry level salary, and does not account for the enormous amounts of debts or other fees (e.g., malpractice) that go along with practicing medicine. So expect to work 10+ years in sweatshop conditions (i.e., 100+ hour work weeks) to pay off all your bills before making decent money.
It's all relative. If say, an OT took out a 100k loan to get his masters degree, and is making 60k per year at entry level, he makes about as much as someone who didn't take out a 100k loan and acquired a 30k per year job. And this would be true for 10-15 years. And if the 30k per year managed to climb the ladder and land a position at 50k per year, he will be better off than the OT for quite some time. Not to mention that he would have a 60k+ head start over the OT since the OT went to OT school without earning a wage for 2+ years.