e.alleg wrote:why don't they make a front wheel drive P/U?
Greg's right; when you load a vehicle aft, it has the effect of "unweighting" the front wheels. If those happen to be the drive wheels, that's not good. So, apart from whatever economic reasons there might be, it just doesn't make engineering sense to have a FWD pickup -- at least not if you're gonna put anything in it! Same thing occurs when you take FWD up a steep hill: putting the vehicle on a slope shifts the load back toward the rear wheels and that can make a critical difference in slippery conditions. If the weight is far enough forward for that not to be a significant problem, the car will understeer badly ("push" is the NASCAR term) when you lose traction on level ground.
OTOH, if loading doesn't change much and you don't have steep slopes to climb, a good FWD setup (I had a great one with traction control a few years back) can do real well. But don't let anybody tell you that FWD is as good as 4WD or AWD, because it just ain't so. It's a law of nature.
But take heart; it's not necessarily an "either or" decision. There are economical AWD choices out there. Look at low-mass (Suzuki SX4, Subaru Impreza) or, as Greg suggests, diesel choices. My AWD Audi S4 has gobs of power, gets 27 honest-injin MPG on the highway, and can pass a plow in the snow.
And don't forget: before 4WD/AWD became common, our parents got around pretty well in the winter by loading a few hundred pounds of weight (bagged coal seems like a pretty convenient idea) over the rear axles of their RWD cars and trucks. And they usually had only 2 "snow tires"!