Here is the light pattern of headlights. Low beams are indeed quite powerful while high beams not that much. My experience is also that this applies only on very flat road. If there are even smallest up/down hills, then light is cut. This is due to very narrow beam output.
It's probably because it's a Bi-Beam LED. This means the low and high beam are of the same intensity. The extra gain in length is just because the shade used to provide low beam moves out of the way to reveal the full view of the light.