In general, family class applications have a very high approval rate, so I am sorry to hear that you have a number of instances of what you believe are disingenuous refusals.
We do request a lot of documents, and if we are not satisfied, if the officers making the decision in the department are not satisfied, applicants can be convoked to an interview to try to establish genuineness of relationship.
However, rest assured that as part of our anti-racism efforts, if there are things we are not seeing from a cultural bias perspective, we hope to uncover those in our evaluation of programs and policies, and we absolutely would like to do better if there is a way to do so.