It's less about the vehicle, I would imagine, and more about the speed.
Yeah, just peddling your bike along a plateau or uphill, you probably wouldn't be going fast enough to be killed by it. Thrown off your bike and hurt, potentially seriously/fatally, sure, but I don't think it'd be likely.
Going downhill though, approaching speeds a dirt bike could do? I could see that decapitating/killing someone, particularly if they use wire. If someone were looking to do harm, they'd put the wires at the bottom of a hill or grade.
But, I've mostly only seen this kind of stuff done on trails frequented by motorcyclists, presumably because the local residents/homeowners don't like the noise of the engines or how they may tear up the trails. Which, to me, is like moving next to a farm and then shooting at the cows because they moo...
Ok, what about passengers?
What about kids? Should they start go right from ABC's to the Tesla Model Y 2020-2021 Owners Manual?
What if it's a rental, do you sit down and read the owners manual in the parking lot of the rental place before you go anywhere?
Door handles have basically been an industry standard as they are (mechanical) because of form and function. They just work, there is zero reason that door handles need to be electric and have a manual emergency release. The only reason I could grasp from the smallest straws was aesthetics: they look cooler/go better with the car.
Lamborghinis and Ferrari's have mechanical door handles, if it's good enough for them, it should be good enough for Musk.