Wags
Here are some pics from the A1U. Since we're lambasting it, may as well use it to prove the point.
In the wide pic, you'll see it to be dimmer and the histograms shows at least 1/5th stop dimmer than the standard.
What you are noticing when you go all wide is that the camera compensating for the added lit subjects, there isn't more light but more lit subjects, giving the illusion of a brighter pic to the naked eye but the camera sees it all.