That's rather arrogant ...

What if his next argument was about being able to hear things coming up behind him? Certainly, that's a lot harder to do with a motorcycle. Coupled with the much better side visibility of a bike helmet vs. a full motorcycle helmet, mirrors seem to be less important. (Disclosure: I ride with a mirror much of the time, and I like it. But it's mostly to help me change lanes, not to warn me of traffic about to overtake me.)

But really, if motorcycles are the chosen metric, why aren't the people who are pushing for mirrors pushing for *two* mirrors? After all, every motorcycle (is this true? read on) has two mirrors.

Side note -- Texas law (to use my state as an example) does indeed seem to require mirrors on motorcycles --

547.602. MIRRORS REQUIRED. A motor vehicle, including a motor vehicle used to tow another vehicle, shall be equipped with a mirror located to reflect to the operator a view of the highway for a distance of at least 200 feet from the rear of the vehicle.

... though it also seems to require windshield wipers --

547.603. WINDSHIELD WIPERS REQUIRED. A motor vehicle shall be equipped with a device that is operated or controlled by the operator of the vehicle and that cleans moisture from the windshield. The device shall be maintained in good working
condition.

(It does not seem to require a windshield, but I can't find anything that exempts vehicles without windshields or motorcycles from 547.603.)