I've been thinking about this a lot, and I think this is a good example of how we could do better as a society;
some people who can't get checking accounts definitely can't handle the responsibility. Most of these people however, handle responsibility 10x as complex as this on a regular basis, and something is missing, either in a lack of shared cultural values (a lot of the unbanked are foreigners I think), or a lack of understanding of consequences (how many times have you heard the "I didn't know I'd fall down this well of overdraft fees"?).
In other words, the people involved usually are trustworthy in a generic "is it safe to bank with them", they're just not plugging into the system in a way that fits the defaults.
I'd almost argue that the banking system ought to be more flexible to maximize its compatibility with as many people as possible, and thus far hasn't because of the drive to maximize certainty and minimize all forms of risk.
I have no answers or real solid ideas for how to do this, but "it's all on them" doesn't quite feel right. These are (mostly) good people who will pay you back if you lend them money, and that should matter!
I think my comment got construed as "people can't change so it's all their fault" and I meant it more as, "financial systems should be willing to move closer to where these people are already at, and stop demanding these people make all the changes."
I also don't know how feasible that is, so... IDK! Just thinking via writing, I guess.