so a few things...
first off, i am willing to bet that olympians know how to bend a ski ;) i am also willing to bet that these ultra elite athletes can want to conserve their fall-line momentum and do not need to put all of their power into the ski on every turn and come too far across the fall line, and therefore feather the degree of bend in their knee to control their trajectory to maximize speed.
second off, i am not saying stick straight, 0 degree bend, i am saying MUCH straighter than the 60-75 degree bend you see in most recreational skiers.
but since you mention it, you might look at pictures of ted ligety (you know... the fastest GS race on the planet...)
here ted in in the 2nd quarter phase of the turn, the downhill leg is basically straight (maybe 10-15 degree bend). the uphill foot has moved forward of the knee, and is engaging the tail of the ski.
here ted is in a 2 foot carve, downhill ski is probably a 10-15 degree bend, and the ball-of-foot of the uphill ski is right @ the patella of the downhill leg. the edge angle on both skis are similar, and the downhill leg's knee is INSIDE of the BOF/HIP
here you can see that ted is carving 2 footed again, but the inside ski's edge angle is higher than the outside ski's edge angle. to maintain power on the outside edge, ted has brought his knee above the line between hip and BOF, and is counter steering with his outside foot. again, the leg is likely 15 degrees.
this turn is most like the pictures posted above, the downhill leg is the most bent (perhaps 25-30 degrees), the uphill ski is beginning the stem, and the ball of foot on the uphill foot trails the patella. is is obvious that ted is trying to make a much tighter turn/going too fast into the turn than in #1, and by putting less power into the edge (i.e. the knee is more bent), with a higher edge angle and stemming the inside foot, can get around the turn without shedding *that* much speed, but there is a ton of spray kicking off the tails of the skis indicating more speed loss that in the first 2 pictures.
all of this is a bit moot, however, unless you are an olympian. all i am saying is work on driving your downhill leg by pushing more into the snow with it, and you will bend the ski more.