There's far more .22 Long Rifle being made than .17 HMR--and in every rimfire factory I've visited they're made on separate assembly lines anyway.
The reason .22 rimfire ammo isn't seen on shelves is some shooters (not all, but some) keep buying it whenever they see it, just as some (not all) shooters feel compelled to post on the Campfire anytime they find any in a store or on an Internet site for what they consider a "reasonable" price.
