We have rental e-scooters around here that come with helmets mounted to the stem for the rider.
I'd say that maybe 1 out of 10 wear the helmet. And you can't imagine how many riders, who have no control over the damn scooter, aren't wearing a helmet.
If someone wants a brain injury, that's fine. But they are burdening anyone and everyone who relies on them and/or has to care for them.