It was an interesting insight and I got inquisitive on why US does not use such mirrors. Found a study by NHTSA if someone is interested to read the details. Pretty comprehensive but for a summary start from chapter 20.
https://one.nhtsa.gov/DOT/NHTSA/NRD/...008/810959.pdf
Full disclosure: I have not read the whole document but have gone through the parts which looked interesting to me