In terms of the merit that counts when in college...maybe? You can't actually tell.
The reason is that merit is not just measured, it's developed. Yes, there's some regression to the mean, but if you haven't developed your skills and you go somewhere that expects you to have developed your skills, it's going to be hard to succeed. So, what do those B's represent? Do they represent someone who has mastered the material and is eager for more, but whose time pressures have prevented them from putting in the time to show it? Or do they represent someone whose life has kept them from really grasping the subject the way that's expected of someone who "has merit"?
One possible way to tell is through standardized testing. But if you can't make the time for that either, it's just the same problem all over again.
(If you don't have time when you go to college, though, that is the same problem yet again...this is an argument for fully funding college, but it is not an argument for taking people who don't have the time to devote to academic excellence and putting them in a place that develops academic excellence.)
This is why California has the community college system: it's specifically there to give space for all college graduates to develop intellectually, with provisions for those who excel to transfer to the UC system (for instance). (The UCs also have a very robust system to look at many aspects of an applicant's life, to try to compensate for the phenomenon you're describing.)
It's designed to reward merit, develop merit, and not assume merit is missing just because scores don't match. But it's all deeply merit-focused. And it works pretty well. Lots of people of all races have come through difficult backgrounds, through the community college system, into UC, and gone on to do amazing things.
If we're doing anecdotes, I have one too. I was in the UC system before Prop 209 abolished affirmative action in the hiring process. I can't say if things improved after prop 209, but I can say that there were people there who were not at all well-served by being there. I tried to tutor them. They tried really hard, I tried really hard (during the comparatively brief time allocated for tutoring)...but by any objective measure, it was a huge waste of their time and effort. You just can't get much out of a physics class, for instance, when you are still struggling with fractions (can do them, but it's a struggle) and the idea that you can represent an undetermined quantity with a letter as part of solving a problem (can do it, but it's a struggle). They were so challenged by the prerequisites that they couldn't absorb much of the material. (Same deal with student athletes let in without adequate academic merit--they didn't get much out of the experience either.)
I hear your tales of rampant doubt and challenge. But I also hear people saying (almost) the opposite: that they never felt particularly doubted (except in encounters with the police). So, how do we resolve the conflicting narratives?
Why, with studies. They can explore fewer nuances (approximately no nuances), but they gather a broader perspective. And doing this--you mentioned studies too, though you didn't cite anything this time--instead of just sticking with narrative and anecdote is part of what I was suggesting as the "beyond CRT" approach. You can also ask--is challenge bad? How bad? (If you provoke stereotype threat, yes, it's bad. If you hold people to standards, it can be good because you push yourself to avoid mediocrity.)
You don't do it with a handful of examples unless the question is whether merit is never rewarded. That was your claim; I came up with five counterexamples not because I thought there were only five but because it illustrated that you were wrong. Is this not clear?
Just because you're bored by large-scale patterns doesn't mean that they're irrelevant. You can be influenced yourself, even, by things you're unaware of. And though initially I had thought that CRT was manufactured outrage over something irrelevant (as this was the standard line given by, say, NPR--and since they normally are pretty trustworthy, I just accepted it), I gradually came to see that the ideas both good and bad had surprisingly wide purchase. It's not all CRT, but if you start digging and questioning and ask "why this?" you often end up with CRT as a significant factor.
Maybe you don't want to dig. Maybe you prefer action and personal contact. Fine! But the "boooooring" stuff just makes you sound juvenile, or at best self-centered. I didn't write it specifically for your entertainment value.