My guess is they keep it that way for simplicity sake, cause from what I've been told, you're better off being a half quart under than a half quart OVER full.
I generally check my oil level whenever I get gas. Shut car off, pump gas, then pop the hood, and adjust if necessary (always carry a quart with me).
Most cars, the ADD mark is only 1 quart low anyways, sure that could be a lot; but you'd be surprised at how many vehicles walmart TLE gets in with "no oil" dipstick checks....according to an acquantaince, sure they have to sign a waiver stating the oil level is low and can't hold WM responsible if say, the engine were to blow the minute they drive it out of the parking lot, but yea, the 4 cyclinders are pretty bullet proof.
Obviously, going too low for too long, you'll end up having gasket problems, wear problems, etc....since their is no oil to cool down the engine, etc.
