....
But it seems there are so many lights with good cut off beams... so why are more people here in the USA not using them or even selling them for that matter ?
My impression is that there is a general lack of awareness of what a beam pattern is, or what patterns/shapes are suitable for different types of riding. A lot of the demand for powerful headlights is for mountain bikes, where a wide beam is useful.
Another factor is that there is no legal requirement (in the USA) for a beam with cutoff. This wasn't a concern with the lights being produced 20 years ago, but with the development of 15 watt MR16 halogen lights, it became relevant. Generally, there have been a few on the market, but they have been designed to comply with the German StVZO standard.
My guess is that while the large suppliers of bike lights know how to make a proper cutoff beam (i.e. B&M, Cateye, ..), a lot of lights are being designed for companies that sell a variety of bike parts and accessories. These companies will go to an electronics design house and tell them to design a light with some general specs. It is likely that neither the bike components company nor the electronics house know anything about optics or beam pattern standards, so the designers just use some commercially available optics or reflector designs and call it good.