The city of course builds shelters for the homeless, and low income housing, a lot of it. But, MARTA money is generated by MARTA operations, and some Federal funding (no state). And the homeless don't use the stations as shelters. Many of the homeless don't want to live in a shelter, not all of course.
The Atlanta Mission does a credible job on a difficult problem, I donate to them regularly.
We still have too many homeless of course, it's distressing. I was surprised how much I saw in DC of folks living in tents.