Been there, done that. Catch yourself on your hands/elbows. If you can’t, then perhaps you should go slower over such terrain. We dutchies coast on average around 20 km/h (12.5 mph). Anyone going above 30 is deemed “racing bicyclist” and they usually do wear helmets. They are a class on their own and are often hated by car drivers, since they think they have the road for themselves.
It sounds like your recommended safety practice is basically not to get hurt and if something does happen to have the strength to stop yourself form flying over the handles bars unexpectedly. This is not a good long term solution. Maybe if you're putzing around town that works ok but if you are ever riding in traffic or at speed this is a recipe for disaster.
So that's the difference. Anybody commuting in America is going as fast as practicable, and owns a road bike. Cruising is more like 32km/h(20mph). Since the average distance from home to work can be many miles, speed is paramount.
Also, any terrain in the US is 'such terrain'. There's little or no accommodation for bikes, and the roads (for cars) consider cracks of 1 inch or so as negligible. Also gratings by curbs (where bikes are expected to ride) often have slots of that size. There's a public-education effort to get gratings turned at right angles to traffic, but most traffic departments are disdainful of bikes.
Bit of a late reply. I find this difference so difficult to grasp. We use our bikes as a utility first and recreation second. Here the bicycles are generally sturdy, heavy, robust. They can take rain, wind, sand, dust for years with minimal maintenance. We don't go fast, but we arrive at our destination without gasping for a breath. Road bikes are seen as unpractical: the chains require weekly maintenance, sitting forward is more dangerous and gives you a bad overview of the road, they don't take rain well (rust) and they wear down relatively fast. Why use them for your commute? It doesn't make sense! It's like taking a sports-car to work every single day. It's fun the first day, but it gets boring, expensive and impractical rather quickly.
