Is there a minimum size requirement for the mirror? You could do the absolute minimal mirror plus a camera. People would get used to the camera and ignore the vestigial mirror and maybe eventually it would go away.
Yes, there are different regs for Europe vs USA. For costs savings, some manufacturers opt for a "global mirror" that is jumbo to cover both regs. In any case, look around at the cars on the street and notice that all are fairly similar in size. Not exactly the easiest requirements to follow: Standard No. 111; Rearview mirrors - Federal Motor Carrier Safety Administration