How frightening! It is so hard when you do not have control over them anymore! Especially when he lives away from home!
The pill box is great, he can see at a glance that he missed. Does he use an alarm of some kind? I have a watch that alarms and have set my cell phone to alarm for my 15 year old daughter. If she does not take it right when it goes off, she often forgets. It is easier for us since I can still be around her to nag! (but she still ignores and skips sometimes!)
he needs to get into a habit...Sounds like he has things set to do that with where he keeps meds etc....
Did he lose his license over the accident? Has his neuro lectured him about why it is so serious to skip meds? Can you get a picture of that wrecked car? It may be that seeing that could remind him what it almost cost him. (not to make him feel overwhelmed for a major goof, but to show a reason why this is so important!!)
you deserve some hazard duty pay!!
Hang in there....