https://www.msn.com/en-us/news/us/this-town-of-170000-replac...
They handle most non-violent 911 calls which cops would end up handling. Things like people walking into a business naked or sleeping in the doorway of a business, these guys get called. It's a big percentage of 911 calls in any city where you have homeless people.
Usually they can help people out, but if people do get violent or belligerent, they call for police backup. That's pretty rare.
Overdoses, sick homeless people, people shouting random shit at people in front of businesses, pretty much anything non violent, these guys talk them down give them a little help, drive them to a clinic, or whatever they need. It's a lot cheaper and more humane than arresting them.
We usually don't want anyone getting in trouble, we just want a tough situation sorted out in a healthy way.