Well,
https://www.google.com/url?sa=t&sour...Ut7rA5mH4SSyOv
Here you go.
There are indeed maximum widths for mirrors in some places. I'm not using this as a biblical proof. I'm using it to show what the true fact MIGHT be.
Either way, mirrors aren't regulated or they are:
It's a fluke or it is the driver. Either driver, either fluke, but I'd like to read the other problems encountered by the op.
I honestly often worry about mirror contact and am surprised it's not a daily event on any stretch of two lane road.