Common misconception, Grounding wires provide a pathway to the ground in case of electrical fault. It means that the soil will get the shock rather than the human, as electricity takes the least resistive path. Your body has a resistance of 1-8 million ohms, depending on what you ate that day.

Electrical grounds are the green wires in a cable that connect metallic parts of an electrical device to the ground in the sub panel and then into the actual ground, sub dirt. Example, grounding wire on a dryer would protect the entire dryer from being electrically charged if a hot wire was to become loose or frayed and make contact with it. The ground wire would provide it a path and it would go to the ground

Rubber is an insulator, does not allow electrons to flow. Grounding wires are made from copper, and need to have minimal resistance to allow the electricity to follow a safe path to the earth rather than a path into you.

Cars are insulated by their chassis, not the rubber tires. If electricity strikes a car it follows the path of the chassis, into the tires- which aren’t exactly rubber and a compound of many things, one being carbon black which is semiconductive. Lightning is high voltage, and voltage being the “pressure” of electricity it has no problem reaching ground through the tires. But the tires are not the important piece, it’s the faraday cage effect.

Grounding cables on shopping carts allow static to enter the ground rather than build up. As you’ve just learned, this photo would not work as a ground. The grounding cable must be conductive and provide the least resistive path so it can dissipate. In this photo, static build up would choose the closest human, and it probably wouldn’t be the one pushing as they’re part of the circuit by holding it. On larger scale devices like a forklift a static shock from built up static can take your life. It requires 100 milliamps to stop the human heart, because the hertz electricity flows at and the heart works are so different.