The OPs point was more about the bickering than what vehicle.
FYI, there are states in the US that don't require motorcycle helmets, which is also part of that bickering.
In terms of risk... a head injury is a head injury... it doesn't necessarily matter how fast you're going or on what vehicle.
I spent 4 years living in Vietnam. Helmets are mandatory there, but few people wear ones that would actually help you in an accident. They just wear a plastic cap that gets past the law. Other countries in SE Asia are similar.
In the Netherlands it went a bit further than mere bickering. There were large scale protests against children being killed in traffic [1]. In the end, instead of introducing more buses or mandating helmets for bicycles, they decided to fix the infrastructure instead.
(other modes of transport still require helmets though, and sometimes also padding)
Some people want to mitigate your injuries in an accident. Helmets definitely stop you banging your head in an accident.
Other people feel that every accident is one too many, and want to prevent accidents outright. If you hardly have any accidents in the first place, the role of helmets is more limited.
(You should still wear a helmet if you're riding a road bike or a mountain bike or what have you, since those kinds of bikes are more dangerous. You should also consider at least wearing a helmet and taking extreme care if your local infrastructure is not (yet) designed to be safe. )
Lower power motor scooters used to be popular in Europe because they didn't require helmets. When the law was changed to make them required, people upgraded to higher power motor scooters (or cars) instead.
FYI, there are states in the US that don't require motorcycle helmets, which is also part of that bickering.
In terms of risk... a head injury is a head injury... it doesn't necessarily matter how fast you're going or on what vehicle.
I spent 4 years living in Vietnam. Helmets are mandatory there, but few people wear ones that would actually help you in an accident. They just wear a plastic cap that gets past the law. Other countries in SE Asia are similar.