Not politically correct, but it does help:
Don't put food, purse, or anything else in the child seat of a shopping cart. Little kids with dirty diapers and leaks through outer clothing sit there. The germs are still there. If the cart was out in the strong sunlight, better, but I wouldn't trust it because I don't know how long it's been there and since it was touched last. Nor can I see very small specks of bodily fluids that may be big enough to not be sanitized all the way through. Plus people's dirty purses and dirty outdoor clothing.
I go to the cart wipes first, get one or two, then go to the carts and take one using a cart wipe. Wiping the entire handle all the way around and all the way across, not just on the plastic handle part, before touching it. If I have shopping bags and/or anything else, to the extent possible, they don't go in the cart. But when I have the refillable glass water bottles, they stay inside the reusable bags and the bags go in a small, no-child-seat type cart, and the bottles don't touch anything (they eventually go in the refrigerator and I definitely don't want to put unnecessary germs in there). If I have time, I can sanitize the whole basket part of the cart, but that takes at least 4 more wipes and at least 5 minutes to do it right (very small no-child-cart)
FWIW, I've thought about bringing in a large sheet of plain newsprint and putting it on the bottom of the cart. The paper's recyclable or disposable, depending on what receptacle(s) are available. Just be careful how one touches it after it's been in the dirty cart.
I've also been known to use produce bags as gloves
Produce bags over each individual meat item (pre-pack or service case). Individual makes it easy for the cashier, and no drips, contamination, etc. in the fridge.
Produce bag used to pick up and package celery, Romaine, peppers, onions, apples, etc., so I don't touch until washing it at home.
It's hard when I have to ask someone to reach a Romaine for me, as it's on the top shelf in the refrigerated/"rained on" produce. For that, always a produce employee, and I look for someone that at least doesn't look sick and is older/more experienced.
I never use a carry basket, as they're always filthy. They get put on the ground, so the bottom picks up whatever's on the floor, and then they get put inside another one when stacked, so the filth gets transferred to the inside of the basket below it. Those baskets also transfer filth to the conveyor belts at check-out.
Some cashiers are better at wiping down the belts, etc. than others, some don't come to work (contagious) sick, etc. The young, teenaged cashiers are usually the least experienced and most likely to be sick. I don't get in a line with sick customers in front of me, either. And not self-service because they're never cleaned, a b'zillion people have touched everything, and trying to help people keep their jobs. Also, no line with a cashier wearing a mask (unless I know he or she wears one even when healthy due to fragrance sensitivities, allergies, immunocompromised, etc.).