The problem in many cases isn't that they don't literally see it but that they aren't aware of what constitutes racism a lot of the time.

I agree with this part, "in many cases" sure,

That's the primary issue here.

...but I think this a strong claim to make unless you have data to back it up.

I believe you and I are likely speaking from our own anecdotal experience on the platform, and for all we know, most people are in instance bubbles and are also speaking from their own perspectives.

If the "primary issue" is "why do some people not report seeing racism?" and the two possible explanations are either "they see it but are not aware" and "they actually never see it", then unless we have accurate data from all those bubbles, we can't make any claims about which is the real explanation.

But if you have data on this, that would change everything.