Why does the wing being "tilted" away from "level" make any difference in the lift being generated compared to the other wing ?
How does the wing know that it is on the low side so it can produce more lift ?
It doesn't decrease the overall lift of the wing, but it tilts the lift vector to the side, which reduces the portion of the lift vector that is now opposing gravity.
As menionted, that's only part of what is going on though.
Btw, some full-scale aircraft appear to have anhedral on the ground, but in the air, the wings flex a lot under heavy load, and are actually rather flat when the plane is being flown as designed. (see B-52)