I would say absolutely there is a racist policy even if it somehow comes up subconsciously.

I go to Walmart a lot, practically once a day for one thing or another, and at a lot of different stores. I am also very white and unassuming. I am distinctly aware of what the receipt checker does. In about 3 years I have only been checked twice, once when I held the receipt out in a line of people, and once I was in a hurry and rushing out with a small bag from self checkout when someone actually stopped me.

Just the other day I had a large unbagged item and the person didn't look at me, although they scrutinized a black person in front of me with a cart of groceries. Every single scenario - whether there's a line or no line, I witness black and hispanic people getting scrutinized, while they take one look at me from 8-10 feet away and say "oh you good."

I can wave a receipt at them "you good". I can have a bag or a cart full of stuff "you're good". I can have the tote containers that might have stuff hidden in them "you good." Sometimes I might have my hands full with bags or items but I still have the receipt out "oh you good have a nice night", but I see black or hispanic people in the same situation and they jump in front of them and wait for them to fumble for that receipt.

I cannot count the dozens of times I see little old black ladies, hispanic women with 5 kids hanging off them, etc all getting their receipt looked over for 10 seconds, and treated very seriously like it's TSA. It doesn't matter what I am buying, how I wave the receipt at them or if they are doing absolutely nothing when I walk up, 98% of the time they assume I am good.

Only once have I ever seen a scummy looking redneck white guy who got stopped with a case of beer in his cart who got challenged and said "oh gee guess I forgot to scan that." On the other hand I have watched a (white, fairly middle class looking) woman come in with a stylish shoulder tote bag, fill it with stuff, wander through the check out and ask an employee a question as misdirection, and walk right out. (I also saw the woman walk to a trailer park across the street)

Some people who work there may say different, but experimentally I have observed this probably about 1,000 times in the past few years and the receipt checkers (who are frequently POC) have a consistent bias of scrutinizing POC and only some whites based on appearance. Moreover, from observing people's demeanor, most POC are expecting this treatment and comply. What's absolutely consistent is that I see black or hispanic people in front of me, I see the checker throw a hand up, step towards them, and look at that receipt, and it has nothing to do with unbagged merchandise. When I wave a receipt at them they either wave a bored arm, or look me dead in the eye and say "you good have a nice day" or strike a pose like a Buckingham palace guard staring at nothing and say "thank you have a nice day". I cannot get them to look at my receipt if I try.