Not to mention while I paid the smart sum of $600 for my kit (a high bar for many to spend on getting started in a hobby), DJI now has an even more approachable model at $299. Making the ability to get into the hobby more accessible is great, but it does come with a greater risk of even well-intentioned but under-educated people (or just knuckleheads) sending a drone up for a quick flight and smashing into someone/something without even reading the manual.
I'm a pretty cautious guy. I took a MSF course before buying a motorcycle, wear a helmet and gear, etc. I was very careful on my first few flights with my drone, but even then managed to crash into a stationary bird house. All this to say I am happy to take a simple test to prove to myself, much less those around me, that I know what the heck I'm doing and to keep myself and others safe because these things are very different from model aircraft and most consumer electronics that include a camera and gyroscopes. :)
I lived a long time before quadcopters became A Thing. I drive by a place (empty, rural field) where sometimes people fly R/C 'copters and airplanes. Lived lots of places. Nonetheless I bet I've seen at least 3x as many quadcopters in my life as other R/C aircraft, almost all in the last 6 or 7 years. I'm not sure I've ever seen those traditional R/C aircraft flying in a neighborhood, or out in a public area, or a small public park (not one with acres of empty space). Maybe a helicopter once? While that's the only place I see quadcopters. Indoors, at parks, at outdoor gatherings of all kinds, weddings, trails, everywhere.
Whether this difference warrants the regulation, I dunno, but there clearly is a difference.