They are quoting the specs of the LED. It takes a certain voltage and current to obtain that light output. There's also a drop in light output from the lens on a light. About 10% IIRC. Then there is beam pattern. If you have a very, very narrow beam, you can light up a penny from a mile away! But that's not useful. The other extreme is the light is spread out over a very large angle. That's not useful because you want more of the light to be focused where you are going. Want to talk about the reflectors in the flashlight? If you read specs on the multi hundred dollar bike lights, they will provide more stats that better indicate what you are buying. And the light will have been engineered to be a useful cycling product. This, in addition to a warranty, contribute to the higher cost of these lights.