Hmmm. I've never had a problem getting a motorcycle on radar. Just as easy as a car. No idea what the experts are talking about, I'm just saying that with 23 years of running radar, motorcycles are just as simple to measure as anything else.
Truth be told, the radar goes out in a cone shape. Laser is as straight and true as an arrow. But radar "sweeps" an area. It will want to register the speed (it can only show one speed at a time) of the biggest and/or the fastest.
As an example, if there's a four lane highway with an 18 wheeler going 85 and three cars going 75, the radar will want to show the 18 wheeler going 85 mph. We can sweep the radar left or right to get the 18 wheeler out of the cone so we can get another vehicle. But the radar will want to show that big object.
If the 18 wheeler is going 65 and a car is passing it at 75, the radar will want to show only the 65 mph 18 wheeler. But once the car breaks away from the truck, the radar will want to display the highest speed.
Four Corvettes across four lanes at 55, 60, 65, and 70, the radar will want to display the 70 mph speed. The law enforcement officer has make the judgement call as to which vehicle is going 70. That's usually easy because it's the car pulling away from the rest or catching up to the rest or simply the one moving the fastest in comparison to the rest.
That's why in court, officers say, "The radar unit confirmed my visual observation."