If you treat your employees like shit ...
then it follows you will treat your customers likewise.
What is to stop an dishonest employee from giving an acquaintance, visiting a store, the goods he wants taken out illegally?
Nothing. I usually decline to do business with stores like that as they usually penalise staff for loses, too.
There is a hotel in Hoi An, VietNam, that uses the same scheme, and after I and a fellow employee (we were on a hotel qualification inspection) filmed the process each day.
After a few days a manager approached me and asked what I was filming. I explained my purpose of checking hotels and that we filmed his 'security' inspections to give negative publicity to our trade clients (travel agents and tour operators) which is part of our business.
A couple of days later it had stopped and, after checking for a year, still remains a thing of the past.
Near my office there is a supermarket where, in public near the store entrance, all employees are scanned and hand searched even if they go to the toilets. And that includes the manager.
I asked him who had key access to the store and he replied five people. I asked what was to stop them returning after hours and pinching something
He replied nothing. I said it was therefore pointless searching them and they, too, stopped.
If employees want to steal product, they will, but that does NOT excuse their employer from humiliating them.