Not Always
If a shopping carts were an electrical appliance they would easily exceed IEC safety guidelines for static electrical discharge into humans. A grounding wire is a poor solution. The problem is the non-conducting, ungrounded floor and triboelectric effects with the cart wheels which generate electrical current continuously as the cart rolls across the floor. The more weight in the cart the higher the electrical current due to rolling/static friction increase.
Wheel contact/friction between acrylic floor finish, polyurethane wheels and metal shopping cart can easily charge the cart to over 20,000 volts multiple times each visit to the store. The child will discharge and get a shock (electrical discharge) every time either they or their parent touch something grounded or at lower potential
‘Shocking’ shopping carts jolt customers
“Millions of Americans shop at big box discount stores. And for most of them it’s a pleasant experience. But a growing number of shoppers have been shocked during a recent store visit. “
I don’t mean “shocked” as in surprised. We’re talking “shocked” as in static electricity. And some have called it a case of “When Shopping Carts Attack.”
Here is a link to an actual test showing 8,000 Volts (electrical potential) easily built up from a grocery store cart. The wheels are generating electrical current continuosly that is flowing into you and your kid’s bodies as you walk down the ailes.
Dark Matters a Lot 
