There is not a separate tier of gifted services for "majority culture" as "bias" would imply
This is not a statement you are able to make about the entire country. In some places and in some schools, parents who are not from the majority culture (this can mean a lot of things) will have a more difficult time advocating for their child. They may not know how to small-talk a teacher in the culturally accepted way, ask the right questions, or network with the right parents to find out what they really need to know. They may simply not be privy to certain networks of knowledge at all.
The examples you give, while unfortunate, also are experienced by "majority culture" parents who are not in the field of education, did not themselves attend public schools and/or participate in gifted programs, may be new to a neighborhood, etc. Therefore, these are not evidence of "bias".
In my community, there is a charter school that never announces the fact that in order to be let in, you MUST sign up to tour the school months in advance of their lottery. Tours accept a limited number of particpants and only run certain times of the year. You have to know people who will tell you that, or you have to be sufficiently motivated to call the school almost a year before your child would enroll. This automatically excludes many people who are not highly motivated and/or "in the know" about the school. This school has very low minority and foreign student enrollment.
Some may say this sounds like an apples-and-oranges comparison:
1) If upon a free phone call to the school, the same information is given to all who may call, then the process may seem fair and equal, not "biased". It seems reasonable that a school may wish to work with parents who've done their homework and have criteria in mind to ensure a good "fit", as compared with a parent looking for anything that is "free" therefore may become disappointed and prove costly (even to the degree of closing a school).
2) On the other hand, if the school accepts government funding and you believe transparency is an issue, you may wish to bring that forward and advocate in a manner designed to bring about change. What change would you envision? Possibly on a webpage about admissions, sharing that consideration for the lottery is given to families on a first-come-first-served basis, therefore the school advises interested families to register in advance for a tour? Or...?
3) Some may say that when we come across something that may not seem right, ethical, best practice, we may choose to use our first amendment rights to speak up for the betterment of the society. There is a saying that if you're not part of the solution you're part of the problem.
