Yeah, a lot of the people who work at the apple stores aren't as knowledgeable as some of the members here. But, there are more new mac users/inexperienced computer users/people who aren't computer savvy than there are mac enthusiast. So, it's okay for the geniuses to know what they know.
A huge part of apple is image. They'll hire a hip, 22 year old, with a scruffy beard, wearing converse, over a 40 year old geek, who knows more about macs than the whole store combined. Obviously the 40 year old geek is more qualified, but it seems to be "image first, knowledge second" with apple. Which doesn't seem to be all bad, because they hipsters can just learn the OS.
Whatever the case is, the fact that a genius doesn't know how to software zoom, isn't a huge deal in my opinion. Most of the people going into the genius bar are new mac users or inexperienced computer users, who have no use for software zoom, and could care less about it. The people who use the computer vigorously, and are mac enthusiast, tend to fix things themselves, and come to a place like marcrumors for aid, thus eliminating the service of a genius.
Like others said in the thread; they probably don't care about macs all that much. It's just they're job, not their hobby (for most of the employees).
My $0.02.
