Our HS had a spirit push last year and the kids in the stands have become extremely supportive of our band. They cheer loudly and enthusiastically at just about the right times.
As for non-band folks, they just don't know the protocol. Plus, they are there for the game and the band is really just half time filler to them I don't expect them to watch and or care. Once a band has a stellar rep, then things will naturally change.