You’re missing the vital forest you started on by getting stuck defining trees it looks like, but I get it.
Minorities are treated by a separate physical rubric by law enforcement and even the court of public opinion. The biases abound, yes. And those absolutely involve secondary physical characteristics, of which biologically speaking are…things that exist. Like skin color is one.
I get what you’re saying and while I don’t know why other folks are uncomfortable with that, but if I clocked things right, your original point (paraphrased below) is damn right imo:
Whether a 16 year old child is American Samoan, Black, Hispanic, or White, they are still a child, however large or mature the specific kid’s genetics may have rolled them to appear. Further, it is fucked up for cops to default to feeling more threatened by the bigger/more developed ones, to have more bombastic reactions, as does tend to happen.
This is reality for minorities; my large colored ass doesn’t get away with certain behaviors even as the affronted party, unfairly as it is.