Just kicking some thoughts around here.
Here are some of the “points of entry” (off the top of my head) whereby persons who have no place to live enter St. Louis’ sojourning population:
A Veterans Administration caseworker relocates them to the area for services.
Greyhound Bus Station/Amtrak
The state and city correctional facilities
With a vehicle (living out of their cars)
or they just lived here all their lives.
And how do they exit the streets?
A charity helps them with a bus ticket out of town.
Temporary work eventually secures them enough money to get out of town.
With the right ID, determination, and a lot of patience the person qualifies for all the needed services to enter housing through a multi-service organization or by eventually making enough extra cash to secure an apartment. (shelter, Employment, transitional housing, drug and alcohol treatment/counseling, shelter + care, etc.)
Accepted for Disability after several appeals.
There are many other ways in and out. Always more ways in then out. To me the most complicating factor is an individuals fierce independence and a refusal to accept anything involving a group home or less than ideal situation.