I agree with your post 100%.
It probably is quite true that a poor person is more likely to divert their medication in order to have money for food or rent, but to not RX on a motive instead of a proven history is wrong. I think a person with more means but motivated by greed would do the same.

There should be no bias when it comes to compassion.
I think it helps to have an established relationship with your doctor, they then get to know you. People on medicaid often have to see a different doc on successive visits.
Especially in inner city clinics.