Vehicle warning lights act as a way for other vehicles to easily spot these trucks and their cargo on the road. This is especially important when driving at night and/or during the rain or other inclement weather. It is during these times when these lights are most valuable and can mean the difference between safety for everyone on the road or utter catastrophe. Factor in other trucks on the road and it can exacerbate the problem. Vehicle lights allow truckers to identify one another and will help avoid collisions that can prove deadly considering their large sizes.
Besides their inherent value as safety tools, vehicle lights also serve as a way for truckers to personalize their cabs and cargo holds. Considering many of the truckers are on the road most days of the year it helps to customize the very vehicles that have housed them and have helped make them a living for years.
You can see the benefits of warning lights for trucks. They are a safety measure which is a great for everyone on the road.