The military is a big employer when it comes to things with wheels. From truck drivers to heavy equipment mechanics and everything in between, modern governments spend millions or even billion in keeping their forces mobile.
Armoured personnel carriers, transport trucks, tanks, jeeps, ATVs, construction equipment and even motorcycles and regular cars have a place in the military. Some of these have a purely combative purpose, while others are part of daily operations. High ranking generals will be chauffeured in staff cars, while military bases will keep motor operated heavy machinery around for everything from clearing snow to military research. Some vehicles serve primarily to tow artillery pieces around, and some are even antiques. All these need in house specialists with auto technician training to maintain them and dispatcher training to see them moved around from point A to point B.
It was Napoleon who was quoted as saying an army moves on its stomach, and when it comes to keeping troops supplied, that much hasn't changed. As a part of home defence, most countries rely more on road than rail, ship or air. The military supplies its employees with everything they need from housing to work clothing and all this needs to be moved around according to the current demands. A quartermaster is the role that oversees inventory of goods, and these days they may have some transport operations training.
Life on base means a regular influx of food and notions, the later to be distributed out of the canteen. Munitions and weapons also need to be moved around. Some of this is obviously going to come from civilian contractors as the military does not keep its own farms and garment manufacturers, but once it is initially delivered, it's up to the organization to move it by truck if it needs to go elsewhere. Communications battalions are in charge of co-ordinating the sort of things that network the organization together, and this might mean dispatcher training, just like if the soldier were a regular worker at a transport company.
During an occupation or invasion, the supply lines still need servicing. The military may even air drop trucks outright, or drive them straight off a boat and to work in the field. They need drivers with steel nerves and they take their mechanics with them. Some even have automotive technician training, as it is difficult to count on having the right people in the right places during the chaos of a war.
Military careers aren't permanent for most people. After their tour of duty, most people look for a civilian job. One of the advantages of working somewhere in the radius of transportation, communications or maintenance is the transferable applicability. With a little extra study, many things from transport operations training to truck driving segue nicely into civilian life.