Theres no reason to put most produce in bags. I don't know why people are obsessed with plastic. People even put bananas in bags... Theyre already bagged!
There is no part of the growing, harvesting, cargo packing, transportation, or store stocking process that's making your produce too pristine to be soiled by a cart. A ride in a bag a couple miles to your house isn't going to sanitize it either.
I use one bag but have my veggies out and separate. And unless it's potatoes and/or any alum family, I tell them to just toss them all in the same bag.