The biggest problem with most U.S. drivers (can't speak for other countries) is few have been taught to use their mirrors.
One CAN NOT be a good driver if one doesn't use them, checking them often! Every 30 seconds to a minute. Situations can change rapidly, look, be aware, know what's around you.
The mirrors are the only way you can determine what is behind or beside you!
Only the mirrors can help determine if your centered in the lane. Only mirrors will tell you how close you are to street signs, fuel pumps, curbs or the trailer or motorhome behind you!
It's not rocket science, but it is a habit we must have to be a good, competent and safe driver!
Unfortunately many never realize the power of them. So sad.
Use those mirrors they will tell the story to keep us all safe.