I'm surprised they haven't. I bet they will.
Another thing I came across in Central America is hospital memberships. An individual pays for a membership and all their medical needs are cared for by that hospital. I believe the Roman Catholic Church has a lot of hospitals.
Not sure if those would work as well...the Knights of Columbus idea you had. One of the reasons these Christian share groups work well is that these groups do live legitimately squeaky clean lives and they are, compared to the average person, squeaky clean honest. These are not churches who would accept the Nancy Pelosi’s of the world as members...if you get my drift.
This risk averse component is a key part of why/how these groups make it work.