I'm not exactly living in Hybrid City USA and I see a Prius or two fairly regularly, as well as a couple (could be the same one) Toyota Highlander Hybrids and a couple Honda Civic Hybrids. It's not as rare as I thought it might be to find myself sitting at a light next to another hybrid vehicle of some sort (in fact, it's happened three times and it always looks staged... Toyota Prius at the stop line of an intersection, me in my FEH behind them.
)
A hybrid here is rare enough that people comment on it, and it takes some effort to find one (FEH) on a lot that has what you want without driving a couple hundred miles. Prius waiting lists here are comparable to other major cities, I am told. My husband took our '92 Toyota Corolla in for an oil change and casually inquired about Toyota Prius availability. All they could offer up offhand was "We've got a used one with hail damage and 11k miles."
I probably see as many hybrids as I do Mini Coopers, Mustang GTs or other lower production run vehicles. If that's a valid comparison criterion, it tells me they're not unpopular just not produced in large enough numbers to make them a highly visible presence on the roadways in many areas.