I'm not sure the example you provide really applies to the situation. Roll cages are mandatory in race cars, so effectively the contrary to "isn't used by profe

I'm not sure the example you provide really applies to the situation. Roll cages are mandatory in race cars, so effectively the contrary to "isn't used by professionals" . Also, they can be used in normal road cars. Granted, they're inconvenient but still provide added safety. An example that comes to mind is Continuously Variable Transmissions (CVT). Most types of motorsports avoid CVTs for reasons of weight, unreliability and decreased repairability. However, for normal road cars, CVTs are very widespread and they do the job just fine (until they don't, but that's another story!)