I’m not a fanatic, but I use Purell after handling restaurant menus and before picking up the silverware or coffee cup.
I also never use the kid’s seat area on shopping carts. That’s where the pee is.
I outgrew those years ago....;)
I usually flip the seat up to keep stuff from falling out but that's a good point.
I also make it a practice to use carts that have been out in the weather, or sitting out in the sun all day. I'll bring them in from the parking lot if need be.
Not that it makes the idea any more pleasant, but urine is sterile (unless the kid had an infection...)