It varies by state, but from what I have heard, MA doesn't require it because (historically) of the cost for the full timers in cities to be licensed. At this point the cost may not be the issue, but I believe historically it was. I believe most departments (including volunteer) in the state have strong driver training programs including documentation because of insurance/liability purposes. It is not the case in MA that you need to be on the way to an emergency, but you do have to be on the job. Especially in rural environments, pump operations is by far the harder skill to learn than driving, even if the truck is 65K lbs with airbrakes. If you are asking this in reference to call/volunteer firefighters, sometime look at the training they have under their belt and you might be impressed. Firefighter I/II certifications, many of them EMTs or greater, driver training etc, and much of the work they do are the thankless tasks to be prepared. The guys who are impressed with their own driving abilities and license levels sometimes have the worst driving records, and often don't last long when they realize the job isn't all flashing lights and sirens. I had my CDL in the past but let it drop years ago when I moved states. Probably a mistake.