There's no problem in putting a lock in the driver's side. It will work upside down from the right, however. You just need to replace the pushbutton in the handle with one that has a lock.
The reason that there is only a lock on the passenger side is that it used to be illegal to exit a vehicle on the driver's side when parked on the curb of a road. It was required that you exit on the curbside. So you would most likely lock the driver door from the inside, then lock the other door from the outside.
BTW-Drivers side door lock was an option.
