I feel like in the training of the new employees, it would behoove certain establishments to bring in outside training help. Like me. SmalWarts (named changed for anonymity) could hire me to boost their crapful image.
I would go slow with them so I wouldn't disrupt their perfect storm of horrible service, dirty stores and rotten produce.
Day one would be pretty low key, not really very informative, perhaps just a little practicing here and there. After a quick session 1, we'd break for lunch then be done for the day. Sort of like this...
"Hi, I am Annie Murphy, you've probably heard of me. I worked in retail for quite some time but won't bore you with the details. Your new employer has asked me to give you a few pointers that will enhance your work experience and make people not hate coming in here.
Number 1. You must smile and say hello, not mumble or mutter but speak. Loudly. So other humans can hear you. Then you mustn't act like you hate the person approaching you making them wonder if you are packin heat, want to slit their throat with the machete you stole from the hunting section of your superstore then put the homemade shank in them you crafted in your downtime of standing around not helping other customers. That's all."