The US is absurd: you don't have to wear a helmet on a motorbike, but you need one on a pedal bike ?!?
There's no national law in the US regarding helmets. It's a state-by-state (and in some cases, city) issue, and most state's don't require that adults wear helmets. That said, I don't know where you get off saying "The US is absurd" when the thing you're calling absurd doesn't exist.
"Don't worry about people stealing your ideas. If your ideas are any good, you'll have to ram them down people's throats." -- Howard Aiken