The circumstances in which organ donation is viable are surprisingly rare. I have a friend who worked in a head injury specialist unit, naturally this was a pretty good source of donors. You ideally need someone who is alive but only by virtue of life support so that you have time to turn off the machine and get the processes started.
The state where I live has opt-in organ donation option when you apply for a driver's license/state ID. As a retired EMT in a rural area, I encountered organ donation cases twice in my career. Once, the patient was flown out, the other time, the orgqan donation crew was flown in. The first case, the patient had suffered a gunshot wound to the head that spared the autonomic functions, he was breathing on his own.