When creating a map as big as American Truck Simulator's needs to be to provide a realistic trucking experience, some corners are going to have to be cut. In order to save on budget and development time, the assets for much of the game's vegetation and a tad sub-par in places.
Those unfamiliar with driving trucks in the real world may fail to realize just how different from other vehicles they can be. One of the major ones is how slowly they pull off from a full stop or the low rate at which they decelerate. The consequences of this are that players pass a traffic light on yellow, but it turns red before they fully cross, leading to a fine.
For legal reasons, the developers of American Truck Simulator can't use any real brands for most of their world. They pay for the licenses to real truck brands, as they are the most important part of the game, but for things like haulage companies, gas stations, and in-game adverts, they created fake companies instead.
Full-time truckers are known to have highly personalized vehicles. Given that it's where they will be spending most of their day, it can be extremely healthy to make it feel as much like home as possible, there are really no limits on this front.
The options the game gives by default are good, but it's nothing like what players would see in real life. This is where the modding community comes in once again, allowing players to add just about anything to their truck. Things on the dashboard, around the cabinet, even letting you put other people or pets inside the truck to travel with the player. Then there are the add-ons, which change the traffic around the truck and add fun things like Star Wars vehicles and passengers.