"从事货车运输业者" can be translated into English as "those engaged in the truck transportation industry" or more concisely as "truck transportation operators" or "truckers (in a professional context, referring to those in the trucking business)".
"Those engaged in the truck transportation industry" clearly specifies the industry and the activity.
"Truck transportation operators" directly refers to the individuals or entities operating in the truck transportation sector.
"Truckers" (when used in a professional or business context) can also refer to those who are professionally involved in trucking, though it's more commonly used in everyday speech to refer to truck drivers. In a more formal or business-oriented context, "truck transportation operators" might be more appropriate.