I am quite convinced they are not safe at all, independant from cars being around and even independent from good separated infrastructure. People falling with bikes tend to break wrists. People falling with scooters tend to break faces. (Both should wear helmets in area with very lacking infrastructure.) But the scooter fallers often fly forwards and don’t even manage to soften the blow with their arms, while most bicycle fallers often fall sideways and do something with their arms that’s softening the blow to the head. It mainly has to do with the size of the wheels, bigger wheels offer more stability and make you less likely to “fly”.
I am quite convinced they are not safe at all, independant from cars being around and even independent from good separated infrastructure. People falling with bikes tend to break wrists. People falling with scooters tend to break faces. (Both should wear helmets in area with very lacking infrastructure.) But the scooter fallers often fly forwards and don’t even manage to soften the blow with their arms, while most bicycle fallers often fall sideways and do something with their arms that’s softening the blow to the head. It mainly has to do with the size of the wheels, bigger wheels offer more stability and make you less likely to “fly”.