I don't know about North Carolina, but in California (at least when I lived there) in order to get a Class I driver's license to drive school busses, etc. you had to take a course in First Aid and pass it in order to get that license level. One of the requirements in the First Aid class was that you were required to give assistance in an actual emergency. People were actually sued for not doing so. They may have overturned that law by now.
As for the mile markers, they aren't really that difficult to follow. They start at the state line, and chenge each mile. Even the exits are marked with corresponding numbers, depending on the nearest mile marker. But if you were to ask the average driver, they wouldn't know that, because there is never an explanation given to new drivers here. If you can mark an "X" in North Carolina, you can get a driver's license. And now you don't even have to speak English.
One of the requirements in the First Aid class was that you were required to give assistance in an actual emergency. People were actually sued for not doing so