The key is "letting them do their jobs". This is very difficult when prosecutors and the city governments are doing everything they can to *not* prosecute theft.
Even if prosecutors refuse to prosecutors there are many actions stores can take to reduce theft.
They can work to identify thieves and ban them from the location. They can catch them and retrieve the merchandise. Chains can share information about the thieves with their other area stores.
There are hundreds of other tactics that can be used, including identifying items most likely to be stolen and placing them behind security cages.
It would be better if prosecutors went after the thieves, but the stores can do a lot.