When I worked there they had hot boxes drivers would carry in their car. There was an alcohol burner in it that somewhat kept it warm. They switched to insulated bags about a year after I started.

The stores usually had one or two company cars, a hatchback like a Ford Escort, painted up with the Domino’s logo. It was not equipped with any special pizza warmer. But most drivers used their own car. They got an hourly wage, a percentage of the order total if they used their own car, and tips.