As I understand it - the biggest segment is men who buy their first bike in their midlife crisis. They buy expensive, large, powerful motorcycles that are difficult to ride and combined with a lack of experience that's basically suicide.

And yeah, when it's a multi-vehicle incident it's still regularly the rider's fault. For example they might crash in a corner and slide across the road into the bullbar of a 4WD coming around the corner in the other direction. Often they're going "too fast" as the police would call it, but realistically the corner could have been navigated safely at the speed they're were travelling... it's just inexperience, combined with the sudden appearance of a scary 4WD coming around the corner, tends to create a momentary panic reaction and the natural reaction is to grab the brakes. Which might serve you well in a car with ABS... but slamming on the brakes hard while leaned over in a corner on a bike will result in a crash every time.

As a rider, I think it should be illegal to ride those bikes until you've got at least 50,000km of experience riding a lighter weight / safer bike. We do (at least in QLD) restrict the type of bike you can ride for the first 12 months, but that's not long enough (I see a lot of new riders who just don't buy a bike their first 12 months after getting a license) and also it's based on power to weight ratio... which is wrong. It should just be based on weight ignoring power. Most accidents happen cornering and braking, and those two have nothing to do with engine power. A lighter bike, however, is much easier to handle when they do start sliding.