In May 2018, the U.S. Congress passed a legislation requiring all new commercial motor vehicles with a gross vehicle weight rating (GVWR) of more than 10,000 pounds manufactured on or after May 2024 to be equipped with rearview video systems or backup cameras.
So, while some 2008 and newer big rigs might have backup cameras installed as optional features if chosen by the buyer at the time of purchase, it didn't become a standard requirement until May 2024. Most newer big rigs produced within the last year and after that mandatory regulation would have built-in backup cameras.