I didn't see the batteries towards the bottom of the listing and just went by the apparent size of the cover. LEDs have gotten better as far as power requirements so that might be why this one has fewer batteries.
LEDs derive their color from the material they are made from for the standard red, green, blue and some of the in between colors. To make white or some of the off colors requires the use of more than one color LED, phosphors or both. This makes the basic color LEDs the most cost effective.
Keith