As more and more companies mandate higher minimum driving ages and cleaner driving records to help reduce their insurance costs, they find themselves needing to hire people who can drive. Some places hire both drivers and non-drivers, and some will not hire someone who is unable to drive the ambulance.
The transport company I work at occasionally has non-drivers, and there are some people who don't like to drive, but will when needed. I've got no problem driving - but when I work transport (once or twice a year), I usually let my partner drive because I have NO CLUE where I'm going.
Some places around me hire people to drive ambulances who aren't EMT’s... then gives them EVOC and a basic EMR class, and cuts them loose to drive (because PA allows that, even on paid rigs).
At the volunteer squad, we have a VERY rigorous driver training program. This means that many people become Crew Chiefs before they are drivers. This also means that are drivers tend to be experienced EMT’s who have been around for a while.
When I work and volunteer on a BLS ambulance, my partner is OFTEN qualified to drive, but not always. When they are qualified, we usually switch, otherwise I get to drive all the time.
At work on the ALS ambulance… I usually drive, except for BLS transports… then my partner drives. Unless my partner wants to drive… then I ride.
Anway – to get back to the OP’s question:
If you are the driver, you will assist in the lifting/moving of the patient, assist in any needed patient care before you start the transport, then assist at the destination. Then you clean up the rig and return it to service (restock, change sheets on cot, clean up and put stuff away in the rig) then you go to then next assignment. You don’t have to worry as much about the paperwork. This is the enjoyment for those of us who have been doing this awhile… but the downside for the new folks is you don’t get any documentation practice.