This is not a new policy. Six years ago, I worked for a store with this policy.
Retail workers have been killed chasing after thieves. Sometimes, lawsuits are filed against the store when the thief is injured.
So, not even the store detectives would chase after thieves. They'd merely take video and photos and hand the evidence over to police.
A few examples from a quick search on FR:
Employee killed trying to prevent liquor store robbery in West Covina
https://freerepublic.com/focus/f-news/4188445/posts
California Home Depot employee shot, killed trying to stop suspected shoplifter
https://freerepublic.com/focus/f-news/4146828/posts
Employee killed while confronting shoplifter taking ammunition
https://freerepublic.com/focus/f-news/4118337/posts
It’s actually pretty standard in the retail world. Don’t put yourself, or anybody else, at risk for the store, the store has insurance.