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.
Reality must take precedence over public relations, for Mother Nature cannot be fooled. -- R.P. Feynman