The problem is that in the US, the colloquialism "stomach flu" is common. It's intended to describe any of various forms of gastroenteritis. These have absolutely nothing to do with influenza, which is a resperatory infection, as you seem well aware. I don't think there's anyone who's not had a bad bout of gastroenteritis, and I'm sure none who have ever want it again. I think many fewer people get influenza in the US than is generally thought due to this common misconception. As such, I think people are thinking they're getting treated for gastroenteritis and line up in droves. If they realized how uncommon the flu is (which is not all that uncommon, but much more so than they think), they'd not bother getting one.

As for me, I get flu-like symptoms from the flu shot, so I don't get one. To me, if it looks like a duck, walks like a duck, and quacks like a duck, it's a duck, so I avoid them to avoid getting the flu. At the same time, I'm pretty sure it's not a live-virus vaccine. I'm almost positive that it's dead, so there really is no chance of actually contracting the flu, but it sure does feel like it.

Edit: It seems that that new nasal mist vaccine is a live virus, but the injectables are not.