You should walk around your car before the road test for the same reasons you should walk around your car before you drive it every time you drive it: to ensure there is nothing in the blind areas around the vehicle (such as children or pets) and to visually check ALL (not just 2) of your tires, and the path between them, and for new damage to the vehicle. It’s also a good habit to check your licence plate; is it there? Does it have valid insurance? When does it expire? Sometimes, plates are stolen.
Read this post for more info: Walk around your car the correct way.
Read about children and vehicle safety: Kids and Cars (.org) *
*Each year, children are injured and killed by vehicles reversing and going forwards because the driver did not perform a proper walk-around before driving to ensure safety.