In the US perhaps, where I live the whole cyclists vs non-cyclist thing does not exist. Everybody is a cyclist (perhaps the US is a car community ;)), but generally in normal clothes, on a normal bike (not racing, but like this [0]), with no helmet and on bike lanes where you never meet a car. The smallest bikes (12 inch wheels) are rated 2-4 years old.
[0] https://duckduckgo.com/?q=cortina+u1&t=ffab&iax=images&ia=im...
Some people wear helmets, but generally it is considered to be such a nuisance (where to leave it, uncomfortable, unnecessary, messes with hear, can't wear a cap) that it may even impede bike usage and make bike less desirable over time. It's certainly not illegal here. There was some research [0], but it's becoming a thing more and more I have to admit [1]. But generally our infra is probably much safer than you can imagine if you've never been here [2]. Also we go quite slow on on our normal bikes (many don't even have gears), we de wear helmets on racing bikes and while mountain biking.
Also, ebikes are making it more unsafe by easily going twice the normal speed, and we need to have a public discussion about that. Many ebike riders do wear helmets, especially the elderly.
[0] https://swov.nl/en/fact/bicycle-helmets-4-why-do-cyclists-ch...
[1] https://www.reddit.com/r/bikecommuting/comments/dwca9c/why_d...
It is generally considered unwise, and depending on age or other circumstances, illegal to ride without a bike helmet, in large part because most places you will meet a car, and if you don’t, wiping out at 15mph is still going to be hard on your noggin.