Since it is not possible to control fir every conceivable influence not to mention any excuse you can concoct, no study can ever meet your “standard”. Add in your conflation of “proof” with evidence, and you completely isolate your position from reason and reality.
Of course perfect controls don't exist, especially in the social sciences. However, they did what appears to be a reasonable job of controlling for the actual financial data--and didn't find discrimination in that regard. They made no effort to control for financial knowledge--and found a lot of discrimination. That says to me they blew it. Studies like this are done with only a few people, one mismatch is enough to blow the whole thing.
More nonsense, some of it just factually incorrect, particularly the last line. You haven’t a clue what you are even talking about. You are certainly not talking about the actual investigations presented. How could you be? Yet again, you have not even looked at them properly. And in the absence of any evidence from the investigations, you almost appear to be implying that certain groups are less likely to have what you describe as sufficient financial knowledge (since you have been offering this as a possible explanation for some of the disparities). There is nothing in the investigations to support this assumption.
And most crucially, this is the sort of thing you always do. It never matters to you what evidence is given, or how much. You continually engage in chronic, pathological denial.
Yes, I am expecting those with a lower home ownership rate to have a lower rate of understanding what's needed to get a mortgage. And I do reject most discrimination evidence because it's flawed. They shouldn't be publishing research that's easy to poke holes in. It's their job to make it solid. We saw them do it properly when it came to qualifications--and note they found no discrimination there.