Following up on this - here is a link to a recent interview with the good friend I mentioned (Bittin Duggan) in previous reply.

https://biamdpodcast.libsyn.com/bitton-duggan-5thoughts-flashback-fakes-funds-and-forests

The interview goes to about ~23 minutes, and then there is other content by the host. In the latter part of the interview Bittin describes her experience of becoming a street/homeless advocate, and how telling her story to people in those situations very frequently leads to them realizing they had some TBI experience somewhere in their past. She says 90% of everyone she works with sounds to have had some form of TBI in their past. If they're not well off and/or well insured, and/or are in a systemically disadvantaged or underserved group, that is the starting point for 'falling through the cracks' as the metaphor goes.