I think in the states the cost in lives might be significant if we did that.
If you look at USPS annual reports to congress they have ~27k motor vehicle accidents a year with a fleet of ~236k vehicles (~216k delivery).[1]
So possibly 10%+ of their vehicles are involved in accidents each year.
If we look at occupant fatality rates for vans (what usps currently use) they're one of the safest vehicle types.[2]
Meanwhile if we look at motorcycles the fatality rate is nearly 10 times higher.[3]
Bicyclist numbers look better at first glance but that's probably because the rate is by total population and not registered vehicles (because you don't have to register a bicycle).[4]
I know in my state (Louisiana), riding a bicycle on a road with other vehicles is considered notoriously unsafe.
Anecdotally I've had friends who reported incidents of people opening doors of moving vehicles to purposefully hit cyclists (and if you search american news media you'll see reports of intentional 'dooring').
It sounds like there could be selection bias in those numbers, so I’m not sure that can be extrapolated. I’d expect that the percentage of vans driven by professional drivers is relatively high, compared to motorcycles.
They separate out minivans from large vans and both types of vans are still some of the safest vehicles.
You could also ignore vans entirely and look at compact cars (the worst of the passenger vehicles) and it's still a bad look for motorcycles.
I don't know that driver quality really matters here.
If you're hit by an SUV or a truck (which is what most americans buy) when you're on a motorcycle it's going to be a worse time than if you're in a vehicle with airbags and crumple zones.
Motorcycles in particular famously have a curve where older people buy them after not riding for a while. I remember seeing a chart showing crashes as a function of recent driver experience and it was IIRC the first 2-3 years which had the highest fatality rate by a surprising margin.
Kids are out of college, house is paid for, nest egg is funded, wife finally lets husband take up his old "dangerous" hobby again. (I'm joking, but also not joking).
Also don't forget about all the young guys who are riding spiritedly everywhere. Even if you're good the inherent risk of that is high and given enough exposure...
That was basically how I heard it from an EMT: guy buys a Harley when he can actually afford it, and wants to ride like he’s 20 but whatever experience he had has atrophied over a couple decades and now his eyesight and reflexes are worse, too.
