It seems to me there's more to the story than simply enforcing current laws. Usually it's a pandering government, which AZ doesn't strike me as being, or a lack of money.
AZ is free to fill their prisons with the homeless thus the taxpayers will be giving them three hots and a cot for months on end as they cycle in and out of the local lock up.
Here's something to consider: most chronically homeless are mentally ill. These people are not rational and won't simply go away. Run them off and they'll come back. Patrol the front sidewalk and they'll go behind the building.
Again, I don't see it as simply enforcing the laws. Which, BTW, is odd. When do Arizona police need permission to enforce the law?
Back when I was being RIF'd out of the Marine Corps and before the Navy processed my package, I was looking at civilian and other government helicopter jobs. Among my top five was the Arizona Highway Patrol for two main reasons; unlike other law enforcement agencies, including the FBI, they didn't require I be a ground officer for two years first. The second was, at the time, a recent incident with bank robbers. Most police helicopters aren't armed. The AZ HP helicopter quickly flew to where the robbers were reported fleeing on a highway. The robbers, being idiots, fired on the helicopter where upon the observer pulled out an M-16 and hosed them down. The car crashed and there were no survivors. My kind of police force. LOL